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Yellowstone River

Yellowstone River

The Yellowstone River is a tributary of the Missouri, approximately 671 mi (1,080 km long), in the western United States. Considered the principal tributary of the upper Missouri, the river and its tributaries drain a wide area stretching from the Rocky Mountains in the vicinity of the Yellowstone National Park across the mountains and high plains of southern Montana and northern Wyoming. It is the longest undammed river in the lower 48 states.

Description

It rises in northwestern Wyoming near Younts Peak at the continental divide in southwestern Park County. It flows northward through Yellowstone National Park, feeding and draining Yellowstone Lake, then dropping through Yellowstone Falls and forming the Grand Canyon of the Yellowstone within the confines of the park. It flows northward into Montana through the Absaroka Range and emerges from the mountains near the town of Livingston, where it turns eastward and northeastward, flowing across the northern Great Plains past the city of Billings. East of Billings, it is joined by the Bighorn River. Further downriver, it is joined by the Tongue near the town of Miles City, and then by the Powder in eastern Montana. It joins the Missouri in extreme western North Dakota, upriver from the town of Williston at the Lake Sakakawea reservoir, with the lower 20 mi (32 km) of the river forming a narrow arm of the reservoir. At the confluence with the Missouri, the Yellowstone is actually the larger river. The river was explored in 1806 by William Clark during the return voyage of the Lewis and Clark Expedition, and the Clarks Fork of the river was named for him. The Clarks Fork collects drainage from the south side of the Beartooth Mountains, runs eastward through Wyoming, and then turns north to run through Clark, Wyoming, Belfry, Montana, Bridger, Montana, and several other towns before joining up with the main river near Billings, Montana. The Yellowstone River was an important artery of transportation for Native Americans as well as for white settlers by riverboat in the 19th century. In Montana, it has been used extensively for irrigation since the 1860s. In its upper reaches, within Yellowstone Park and the mountains of Montana, it is a popular destination for fly fishing.

External links

- [http://endangered.fws.gov/uppermo.html Fish and Wildlife Service: Upper Missouri River and Yellowstone]
- [http://nd.water.usgs.gov/lewisandclark/yellowstone.html USGS Site: Lewis and Clark Expedition]
- [http://nris.state.mt.us/yellowstone/UpperYel/document/user.html State of Montana: Yellowstone River Physical Features Inventory]
- [http://nris.state.mt.us/yellowstone/LowerYel/LowerYelPhotos.html State of Montana: Lower Yellowstone Corridor Physical Features Inventory]
- [http://www.flyfishingconnection.com/yellowstone.html Fly Fishing the Yellowstone]
- [http://www.bigskyfishing.com/River-Fishing/South-MT-Rivers/yellowstone-river/photo_gallery/YellowstoneRiverPhotographs/index.htm Yellowstone River Pictures] Category:Rivers of Montana Category:Rivers of North Dakota Category:Rivers of Wyoming Category:Tributaries of the Missouri River Category:Yellowstone ja:イエローストーン川

United States

:For alternative meanings, see the disambiguation page for US, USA, United States, or American. The United States of America is a federal democratic republic situated primarily in central North America. It comprises 50 states and one federal district, and has several territories. It is also referred to, with varying formality, as the United States, the U.S., the U.S.A., the States, or simply and most commonly, America. The official founding date of the United States is July 4, 1776, when the Second Continental Congress—representing thirteen British colonies—adopted the Declaration of Independence. However, the structure of the government was profoundly changed in 1788, when the states replaced the Articles of Confederation with the United States Constitution. The date on which each of the fifty states adopted the Constitution is typically regarded as the date that state "entered the Union" (became part of the United States). Since the mid-20th century, following World War II, the United States has emerged as a dominant global influence in economic, political, military, scientific, technological, and cultural affairs.

Geography and climate

The United States shares land borders with Canada (to the north) and Mexico (to the south), and territorial water boundaries with Canada, Russia, the Bahamas, and numerous smaller nations. It is otherwise bounded by the Pacific Ocean and the Bering Sea, in the west; the Arctic Ocean, in the northernmost areas; and the Atlantic Ocean, the Gulf of Mexico, and the Caribbean Sea, in the eastern and southeastern areas. Forty-eight of the states are in the single region between Canada and Mexico; this group is referred to, with varying precision and formality, as the continental or contiguous United States, sometimes abbreviated CONUS, and as the Lower 48. Alaska, which is not included in the term contiguous United States, is at the northwestern end of North America, separated from the Lower 48 by Canada. The archipelago of Hawaii is in the Pacific Ocean. The capital city, Washington, District of Columbia is a federal district located on land donated by the state of Maryland. (Virginia also donated land, but it was returned in 1847.) The United States also has overseas territories with varying levels of independence and organization. When inland water is included in the total area, only Russia and Canada are larger than the United States; if inland water is excluded, China ranks third and the U.S. ranks fourth. The United States' total area is 3,718,711 square miles (9,631,418 km²), of which land makes up 3,537,438 square miles (9,161,923 km²) and water makes up 181,273 square miles (469,495 km²). The United States' landscape is one of the most varied among those of the world's nations: among its many features are temperate forestland and rolling hills, on the east coast; mangrove, in Florida; the Great Plains, in the center of the country; the Mississippi–Missouri river system; the Great Lakes, four of the five of which are shared with Canada; the Rocky Mountains, west of the Great Plains; deserts and temperate coastal zones, west of the Rocky Mountains; and temperate rain forests, in the Pacific northwest. Alaska's tundra, and the volcanic, tropical islands of Hawaii add to the geographic diversity. Hawaii The climate varies along with the landscape, from tropical in Hawaii and southern Florida to tundra in Alaska and atop some of the highest mountains. Most of the North and East experience a temperate continental climate, with warm summers and cold winters. Most of the South experiences a subtropical humid climate with mild winters and long, hot, humid summers. Rainfall decreases markedly from the humid forests of the Eastern Great Plains to the semi-arid shortgrass prairies on the high plains abutting the Rocky Mountains. Arid deserts, including the Mojave, extend through the lowlands and valleys of the southwest, from westernmost Texas to California and northward throughout much of Nevada. Some parts of California have a Mediterranean climate. Rainforests line the windward mountains of the Pacific Northwest from Oregon to Alaska.

History

American history started with the migration of people from Asia across the Bering land bridge approximately 12,000 years ago following large animals that they hunted into the Americas. These Native Americans left evidence of their presence in petroglyphs, burial mounds, and other artifacts. It is estimated that 2-9 million people lived in the territory now occupied by the U.S. before European contact, and the subsequent introduction of foreign diseases such as small pox that greatly diminished the native populations. Some advanced societies were the Anasazi of the southwest, who inhabited Chaco Canyon, and the Woodland Indians, who built Cahokia, located near present-day St Louis, a city with a population of 40,000 at its peak in AD 1200. Vikings first visited North America around 1000, but did not settle permanently. Following the discovery voyages of Christopher Columbus around 1492, other Europeans began to explore and settle there. During the 1500s and 1600s, the Spanish settled parts of the present-day Southwest and Florida, founding St. Augustine, Florida in 1565 and Santa Fe (in what is now New Mexico) in 1607. The first successful English settlement was at Jamestown, Virginia, also in 1607. Within the next two decades, several Dutch settlements, including New Amsterdam (the predecessor to New York City), were established in what are now the states of New York and New Jersey. In 1637, Sweden established a colony at Fort Christina (in what is now Delaware), but lost the settlement to the Dutch in 1655. This was followed by extensive British settlement of the east coast. The British colonists remained relatively undisturbed by their home country until after the French and Indian War, when France ceded Canada and the Great Lakes region to Britain. Britain then imposed taxes on the 13 colonies, widely regarded by the colonists as unfair because they were denied representation in the British Parliament. Tensions between Britain and the colonists increased, and the thirteen colonies eventually rebelled against British rule. British Parliament, George Washington (1789-1797).]] In 1776, the 13 colonies split from Great Britain and formed the United States, the world's first constitutional and democratic federal republic, after their Declaration of Independence of that year, and the Revolutionary War (1775 to 1783). The original political structure was a confederation in 1777, ratified in 1781 as the Articles of Confederation. After long debate, this was supplanted by the Constitution in 1789, forming a more centralized federal government. Prior to all these was the Albany Congress in 1754, in which a union was first seriously proposed. From early colonial times, there was a shortage of labor, which encouraged unfree labor, particularly indentured servitude and slavery. In the mid-19th century, a major division occurred in the United States over the issue of states' rights and the expansion of slavery. The northern states had become opposed to slavery, while the southern states saw it as necessary for the continued success of southern agriculture and wanted it expanded to the territories. Several federal laws were passed in an attempt to settle the dispute, including the Missouri Compromise and the Compromise of 1850. The dispute reached a crisis in 1861, when seven southern states seceded¹ from the Union and formed the Confederate States of America, leading to the Civil War. Soon after the war began, four more southern states seceded. During the war, Abraham Lincoln issued the Emancipation Proclamation, mandating the freedom of all slaves in states in rebellion, though full emancipation did not take place until after the end of the war in 1865, the dissolution of the Confederacy, and the Thirteenth Amendment took effect. The Civil War effectively ended the question of a state's right to secede, and is widely accepted as a major turning point after which the federal government became more powerful than state governments. Thirteenth Amendment). The title of the painting, from a 1726 poem by Bishop Berkeley, was a phrase often quoted in the era of Manifest Destiny, expressing a widely held belief that civilization had steadily moved westward throughout history. [http://americanart.si.edu/t2go/1lw/1931.6.1.html (more)] ]] During the 19th century, many new states were added to the original 13 as the nation expanded across the continent. Manifest Destiny was a philosophy that encouraged westward expansion in the United States. As the population of the Eastern states grew and as a steady increase of immigrants entered the country, settlers moved steadily westward across North America. In the process, the U.S. displaced most American Indian nations. This displacement of American Indians continues to be a matter of contention in the U.S. with many tribes attempting to assert their original claims to various lands. In some areas American Indian populations were reduced by foreign diseases contracted through contact with European settlers, and US settlers acquired those emptied lands. In other instances American Indians were removed from their traditional lands by force. Though some would say the U.S. was not a colonial power until the Spanish-American War when it acquired Puerto Rico, Guam and the Philippines, the dominion exercised over land in North America the United States claimed is essentially colonial. The Philippines became independent in 1946. During this period, the nation also became an industrial power. This continued into the 20th century, which has been termed "the American Century" because of the nation's overriding influence on the world. The US became a center for innovation and technological development; major technologies that America either developed or was greatly involved in improving include the telephone, television, computer, the Internet, nuclear weapons, nuclear power, aviation, and aeronautics. In addition to the Civil War, another major traumatic experience for the nation was the Great Depression (1929 to 1939). The nation has also taken part in several major foreign wars, including World War I and World War II (in both of which the US later joined the Allies). During the Cold War, the US was a major player in the Korean War and Vietnam War, and, along with the Soviet Union, was considered one of the world's two "superpowers". With the collapse of the Soviet Union, the US emerged as the world's leading economic and military power. Beginning in the 1990s, the United States became very involved in police actions and peacekeeping, including actions in Kosovo, Haiti, Somalia and Liberia, and the first Persian Gulf War driving Iraq out of Kuwait. After attacks on the World Trade Center and the Pentagon on September 11, 2001, the United States and other allied nations found themselves involved in what has come to be called the "War on Terrorism," which has primarily encompassed military actions in both Afghanistan and Iraq.

Government

Iraq of the United States.]]

Republic and suffrage

The United States is an example of a constitutional republic, with a government composed of and operating through a set of limited powers imposed by its design and enumerated in the United States Constitution. Specifically, the nation operates as a presidential democracy. There are three levels of government: federal, state, and local. Officials of each of these levels are either elected by eligible voters via secret ballot or appointed by other elected officials. Americans enjoy almost universal suffrage from the age of 18 regardless of race, sex, or wealth. There are some limits, however: felons are disenfranchised and in some states former felons are likewise. Furthermore, the national representation of territories and the federal district of Washington, DC in Congress is limited: residents of the District of Columbia are subject to federal laws and federal taxes but their only Congressional representative is a non-voting delegate.

Federal government

The federal government is the national government, comprising the Legislative Branch (led by Congress), the Executive Branch (led by the President), and the Judicial Branch (led by the Supreme Court). These three branches were designed to apply checks and balances on each other. The Constitution limits the powers of the federal government to defense, foreign affairs, the issuing and management of currency, the management of trade and relations between the states, and the protection of human rights. In addition to these explicitly stated powers, the federal government—with the assistance of the Supreme Court—has gradually extended these powers into such areas as welfare and education, on the basis of the "necessary and proper" clause of the Constitution.

The Congress

necessary and proper The Congress of the United States is the legislative branch of the federal government of the United States. It is bicameral, comprising the House of Representatives and the Senate. The House of Representatives consists of 435 members, each of whom represents a congressional district and serves for a two-year term. House seats are apportioned among the states by population; in contrast, each state has two Senators, regardless of population. There are a total of 100 senators, who serve six-year terms. The powers of Congress are limited to those enumerated in the Constitution; all other powers are reserved to the states and the people. The Constitution also includes the necessary-and-proper clause, which grants Congress the power to "make all laws which shall be necessary and proper for carrying into execution the foregoing powers."

The President

necessary-and-proper clause At the top level of the executive branch is the President of the United States. The President and Vice-President are elected as 'running mates' for four-year terms by the Electoral College, for which each state, as well as the District of Columbia, is allocated a number of seats based on its representation (or ostensible representation, in the case of D. C.) in both houses of Congress (see U.S. Electoral College). The relationship between the President and the Congress reflects that between the English monarchy and parliament at the time of the framing of the United States Constitution. Congress can legislate to constrain the President's executive power, even with respect to his or her command of the armed forces; however, this power is used only very rarely—a notable example was the constraint placed on President Richard Nixon's strategy of bombing Cambodia during the Vietnam War. The President cannot directly propose legislation, and must rely on supporters in Congress to promote his or her legislative agenda. The President's signature is required to turn congressional bills into law; in this respect, the President has the power—only occasionally used—to veto congressional legislation. Congress can override a presidential veto with a two-thirds majority vote in both houses. The ultimate power of Congress over the President is that of impeachment or removal of the elected President through a House vote, a Senate trial, and a Senate vote. The threat of using this power has had major political ramifications in the cases of Presidents Andrew Johnson, Richard Nixon, and Bill Clinton. The President makes around 2,000 executive appointments, including members of the Cabinet and ambassadors, which must be approved by the Senate; the President can also issue executive orders and pardons, and has other Constitutional duties, among them the requirement to give a State of the Union address to Congress once a year. Although the President's constitutional role may appear to be constrained, in practice, the office carries enormous prestige that typically eclipses the power of Congress: the Presidency has justifiably been referred to as 'the most powerful office in the world'. The Vice President is first in the line of succession, and is the President of the Senate ex officio, with the ability to cast a tie-breaking vote. The members of the President's Cabinet are responsible for administering the various departments of state, including the Department of Defense, the Justice Department, and the State Department. These departments and department heads have considerable regulatory and political power, and it is they who are responsible for executing federal laws and regulations. George W. Bush is the 43rd President, currently serving his second term.

The Courts

George W. Bush The highest court is the Supreme Court, which consists of nine justices. The court deals with federal and constitutional matters, and can declare legislation made at any level of the government as unconstitutional, nullifying the law and creating precedent for future law and decisions. Below the Supreme Court are the courts of appeals, and below them in turn are the district courts, which are the general trial courts for federal law. Separate from, but not entirely independent of, this federal court system are the individual court systems of each state, each dealing with its own laws and having its own judicial rules and procedures. A case may be appealed from a state court to a federal court only if there is a federal question; the supreme court of each state is the final authority on the interpretation of that state's laws and constitution.

State and local governments

supreme court of each state. Note that Alaska and Hawaii are shown at different scales, and that the Aleutian Islands and the uninhabited Northwestern Hawaiian Islands are omitted from this map.]] The state governments have the greatest influence over people's daily lives. Each state has its own written constitution and has different laws. There are sometimes great differences in law and procedure between the different states, concerning issues such as property, crime, health, and education. The highest elected official of each state is the Governor. Each state also has an elected legislature (bicameral in every state except Nebraska), whose members represent the different parts of the state. Of note is the New Hampshire legislature, which is the third-largest legislative body in the English-speaking world, and has one representative for every 3,000 people. Each state maintains its own judiciary, with the lowest level typically being county courts, and culminating in each state supreme court, though sometimes named differently. In some states, supreme and lower court justices are elected by the people; in others, they are appointed, as they are in the federal system. The institutions that are responsible for local government are typically town, city, or county boards, making laws that affect their particular area. These laws concern issues such as traffic, the sale of alcohol, and keeping animals. The highest elected official of a town or city is usually the mayor. In New England, towns operate directly democratically, and in some states, such as Rhode Island and Connecticut, counties have little or no power, existing only as geographic distinctions. In other areas, county governments have more power, such as to collect taxes and maintain law enforcement agencies.

Political divisions

With the Declaration of Independence, the thirteen colonies proclaimed themselves to be nation states modeled after the European states of the time. Although considered as sovereigns initially, under the Articles of Confederation of 1781 they entered into a "Perpetual Union" and created a fully sovereign federal state, delegating certain powers to the national Congress, including the right to engage in diplomatic relations and to levy war, while each retaining their individual sovereignty, freedom and independence. But the national government proved too ineffective, so the administrative structure of the government was vastly reorganized with the United States Constitution of 1789. Under this new union, the continued status of the individual states as sovereign nation states fell into dispute in 1861, as several states attempted to secede from the union; in response, then-President Abraham Lincoln claimed that such secession was illegal, and the result was the American Civil War. Since the Union victory in 1865, the independent status of the individual states has not been broached again by any state, and the status of each state within the union has been deemed by mainstream officials and academics to be settled as being subordinate to the union as a whole. In subsequent years, the number of states grew steadily due to western expansion, the purchase of lands by the national government from other nation states, and the subdivision of existing states, resulting in the current total of 50. The states are generally divided into smaller administrative regions, including counties, cities and townships. The United States–Canadian border is the longest undefended political boundary in the world. The U.S. is divided into three distinct sections:
- the "continental United States," also known as "the Lower 48" and more accurately termed the conterminous, coterminous or contiguous United States
- Alaska, which is physically connected only to Canada
- the archipelago of Hawaii, in the central Pacific Ocean. The United States also holds several other territories, districts, and possessions, notably the federal district of the District of Columbia, which is the nation's capital, and several overseas insular areas, the most significant of which are American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, and the United States Virgin Islands. The Palmyra Atoll is the United States' only incorporated territory; it is unorganized and uninhabited. The United States Navy has held a base at a portion of Guantanamo Bay, Cuba, since 1898. The United States government possesses a lease to this land, which only mutual agreement or United States abandonment of the area can terminate. The present Cuban government of Fidel Castro disputes this arrangement, claiming Cuba was not truly sovereign at the time of the signing. The United States argues this point moot because Cuba apparently ratified the lease post-revolution, and with full sovereignty, when it cashed one rent check in accordance with the disputed treaty.

Foreign relations and military

sovereign] The immense military and economic dominance of the United States has made foreign relations an especially important topic in its politics, with considerable concern about the image of the United States throughout the world. Reactions towards the United States by other nationalities are often strong, ranging from uninhibited admiration and mimicking of all things American to anti-Americanism. US foreign policy has swung about several times over the course of its history between the poles of strict isolationism and imperialism and everywhere in between. Three of the nation's four military branches are administered by the Department of Defense: the Army, the Navy (including the Marine Corps), and the Air Force. The Coast Guard falls under the jurisdiction of the Department of Homeland Security in peacetime, but is placed under the Department of the Navy in time of war. The combined United States armed forces consist of 1.4 million active duty personnel, along with several hundred thousand each in the Reserves and the National Guard. Military conscription ended in 1973. The United States Armed forces are considered to be the most powerful military (of any sort) on Earth and their force projection capabilities are unrivaled by any other nation. The 2005 defense budget amounted to $401.7 billion, which is an increase of 4% over 2004 and of 35% since 2001. Over 50% of that number is spent in research & development. (For comparison, in 2004 the European Union (considered as the second-largest military force) had a combined total of 1.6 million troops, and a defense budget of €160 billion, with less than 10% of that being spent on R&D.)

Largest cities

The United States has dozens of major cities, including 11 of the 55 global cities of all types — with three "alpha" global cities: New York City, Los Angeles, and Chicago. The figures expressed below are for populations within city limits. A different ranking is evident when considering U.S. metro area populations, although the top three would be unchanged. Note that some cities not listed (such as Atlanta, Boston, Las Vegas, Miami, Nashville, New Orleans, Seattle, and Washington, D.C.) are still considered important on the basis of other factors and issues, including culture, economics, heritage, and politics. The twenty largest cities, based on the United States Census Bureau's 2004 estimates, are as follows:

Economy

The United States has the largest single-country economy in the world, with a per-capita gross domestic product of $40,100. In this market-oriented economy, private individuals and business firms make most of the decisions, and the federal and state governments buy needed goods and services predominantly in the private marketplace. gross domestic product The largest industry of the U.S. is now service, which employs roughly three quarters of the U.S. work force. The United States has many natural resources, including oil and gas, metals, and such minerals as gold, soda ash, and zinc. In agriculture, the U.S. is a top producer of, among other crops, corn, soy beans, and wheat; the United States is a net exporter of food. The U.S. manufacturing sector produces goods such as, cars, airplanes, steel, and electronics, among many others. Economic activity varies greatly from one part of the country to another, with many industries being largely dependent on a certain city or region; New York City is the center of the American financial, publishing, broadcasting, and advertising industries; Silicon Valley is the country’s primary location for high-technology companies, while Los Angeles is the most important center for film production. The Midwest is known for its reliance on manufacturing and heavy industry, with Detroit, Michigan, serving as the center of the American automotive industry; the Great Plains are known as the "breadbasket" of America for their tremendous agricultural output; the intermountain region serves as a mining hub and natural gas resource; the Pacific Northwest for fish and timber, while Texas is largely associated with the oil industry; the Southeast is a major hub for both medical research and the textiles industry. Several countries continue to link their currency to the dollar or even use it as a currency (such as Ecuador), although this practice has subsided since the collapse of the Bretton Woods system. Many markets are also quoted in dollars, such as those of oil and gold. The dollar is also the predominant reserve currency in the world, and more than half of global reserves are in dollars. The largest trading partner of the United States is Canada (19%), followed by China (12%), Mexico (11%), and Japan (8%). More than 50% of total trade is with these four countries. In 2003, the United States was ranked as the third most visited tourist destination in the world; its 40,400,000 visitors ranked behind France's 75,000,000 and Spain's 52,500,000. Labor unions have existed since the 19th century, and grew large and powerful from the 1930s to the 1950s. See Labor history of the United States. Since 1970 they have shrunk in the private sector and now cover fewer than 8% of the workers. However union membership has grown rapidly in the public sector, especially among teachers, nurses, police, postal workers, and municipal clerks. There have been few strikes in recent years. The United States' imports exceed exports by 80%, leading to an annual trade deficit of $700,000,000,000, or 6% of gross domestic product. It is the largest debtor nation in the world, with total gross foreign debt of over $13,000,000,000,000 (2005 estimate); and it absorbs more than 50% of global savings annually. Since the 1980s, the U.S. has increased the use of neoliberal economic policies that reduce government intervention and reduce the size of the welfare state, backing away from the more interventionist Keynsian economic policies that had been in favor since the Great Depression. As a result, the United States provides fewer government-delivered social welfare services than most industrialized nations, choosing instead to keep its tax burden lower and relying more heavily on the free market and private charities. Sixteen states and the District of Columbia have minimum wages higher than the national level ($5.15 per-hour), including the highest, Washington State at $7.35. Twenty-six states are the same as the federal level; two--Ohio and Kansas--are below; and six do not have state laws. America's wealth is relatively highly concentrated. The average C.E.O. earns 500 times the typical amount a worker grosses, this is up from 25 times in the late 1970s. In terms of wealth the top 1% of Americans own 40% of all assets and 50.1% of the country's income goes to the top twenty percent of households. Average wages for the majority of employees have been largely stagnating since the 1970s. America's poverty line defined as a family of four earning less than $19,157 is at 12.7% of the general population. Approximately one out of every five children in the United States grows up below the official poverty line. Among racial groups; African Americans have the lowest median income while Asians had the highest. Regionally, the southern states had the lowest median incomes while the West Coast and New England had the highest. The current Federal Reserve Chairman Alan Greenspan remarked that the U.S.’s growing income inequality since the 1970s is, "not the type of thing which a democratic society - a capitalist democratic society - can really accept without addressing."[http://www.csmonitor.com/2005/0614/p01s03-usec.html?s=itm] However, Greenspan also noted, "...you can look at the system and say it's got a lot of problems to it, and sure it does. It always has. But you can't get around the fact that this is the most extraordinarily successful economy in history."

Transportation

Alan Greenspan ]] Because the United States is a relatively young nation, most of the development of U.S. cities has taken place since the invention of the automobile. To link its vast territory, the United States built a network of high-capacity, high-speed highways, of which the most important element is the Interstate Highway system, commissioned in the 1950s by President Dwight D. Eisenhower and modeled after the German Autobahn. The United States also has a transcontinental rail system, which is used for moving freight across the lower forty-eight states. Passenger rail service is provided by Amtrak, which serves forty-six of the lower forty-eight states. Many cities in the United States have extensive mass-transit systems. New York City operates one of the world's largest and most heavily used subway systems. The regional rail and bus networks that extend into Long Island, New Jersey, Upstate New York, and Connecticut are among the most heavily used in the world. Air travel is often preferred for destinations over 300 miles (500 kilometers) away. In terms of passengers, seventeen of the world's thirty busiest airports in 2004 were in the U.S., including the world's busiest, Hartsfield-Jackson Atlanta International Airport; in terms of cargo, in the same year, twelve of the world's thirty busiest airports were in the U.S., including the world's busiest, Memphis International Airport. There are several major seaports in the United States; the three busiest are the Port of Los Angeles, California; the Port of Long Beach, California; and the Port of New York and New Jersey. Others include Houston, Texas; Charleston, South Carolina; Savannah, Georgia; Miami, Florida; Portland, Oregon; San Francisco, California; Boston, Massachusetts; Philadelphia, Pennsylvania; and Seattle, Washington; plus, outside the contiguous forty-eight states, Anchorage, Alaska, and Honolulu, Hawaii.

Society

Demographics

Hawaii The mean center of the U.S. population continues to drift farther west and south. The fastest growing region is the western United States followed by the southern portion. According to Census 2000, the states that saw the greatest increases from 1990 were: Nevada (66.3%), Arizona (40%), Colorado (30.6%), Utah (29.6%), Idaho (28.5%), Georgia (26.4%), Florida (23.5%), Texas (22.8%), North Carolina (21.4%), and Washington (21.1%). [http://www.census.gov/population/cen2000/phc-t2/tab03.pdf]

Ethnicity and race

:Main article: Racial demographics of the United States The United States is a very racially diverse country. According to the 2000 census, it has 31 ethnic groups with at least one million members each, and numerous others represented in smaller amounts. The majority of Americans descend from white European immigrants who arrived at the establishment of the first colonies (most after Reconstruction). This majority--69.1% in 2000--decreases each year, and is expected to become a plurality within a few decades. The most frequently stated European ancestries are German (15.2%), Irish (10.8%), English (8.7%), Italian (5.6%) and Scandinavian (3.7%). Many immigrants also hail from Slavic countries such as Poland and Russia. Other significant immigrant populations came from eastern and southern Europe and French Canada. Russia Hispanics from Mexico and South and Central America are the largest minority group in the country, comprising 12.5% of the population (2000 census). People of Mexican descent made up 7.3% of the population in the 2000 census, and this proportion is expected to increase significantly in the coming decades. About 12.3% (2000 census) of the American people are African Americans (Blacks). African Americans are spread throughout the country, but their presence is largest in the South. Asian Americans--including Native Hawaiians and Pacific Islanders--are a third significant minority (3.7% of the population in 2000). Most Asian Americans are concentrated on the West Coast and Hawaii. The largest groups are immigrants or descendants of emigrants from the Philippines, China, India, Vietnam, South Korea, and Japan. Indigenous peoples in the United States, such as American Indians and Inuit, make up 0.9% of the population (2000 census). About 35% live on Indian reservations.

Religion

Polls estimate that just under 80 percent of Americans are Christians of various denominations. The other 20 percent comprises other religions such as Hinduism, Judaism, Islam, and Buddhism, other various faiths, and those without a specific religion. The United States is noteworthy among developed nations for its relatively high level of religiosity. According to a 2004 Gallup poll, about 44% of Americans attend a religious service at least once a week. However, this rate is not uniform across the country; attendance is more common in the Bible Belt—composed largely of Southern and Midwestern states—than in the Northeast and West Coast. In the Southern states, Baptists are the largest group, followed by Methodists; Roman Catholics are dominant in the Northeast and in large parts of the Midwest due to their being settled by descendants of Catholic immigrants from Europe (such as Germany, Ireland, Italy, and Poland) or other parts of North America (mainly Quebec and Puerto Rico). The rest of the country for the most part has a complex mixture of various Christian groups.

Education

West Coast's home at Monticello and the University of Virginia (library building shown above, and designed by Jefferson), the only collegiate campus on the list. Both sites are located in Charlottesville, Virginia.]] In the United States, education is a state, not federal, responsibility, and the laws and standards vary considerably. However, the federal government, through the Department of Education, is involved with funding of some programs and exerts some influence through its ability to control funding. In most states, all students must attend mandatory schooling starting with kindergarten, which children normally enter at age 5, and following through 12th grade, which is normally completed at age 18

Rocky Mountains

:This is an article about the Rocky Mountains. For the American Major League Baseball team, see Colorado Rockies. For the National Hockey League Rockies team (1976–1982), see Colorado Rockies (NHL) Colorado Rockies (NHL)]] The Rocky Mountains, often called the Rockies, are a broad mountain range in western North America. The Rocky Mountains stretch more than 3,000 miles (4,800 kilometers) from British Columbia, in Canada, to New Mexico, in the United States. The highest peak is Mount Elbert, in Colorado, which is 14,440 feet (4,401 meters) above sea level. Mount Robson, at 12,972 feet (3,954 meters) is the highest peak in the Canadian Rockies. The Rocky Mountain System is a United States physiographic region.

Geography and geology

United States physiographic region, Wyoming]] The Rocky Mountains are commonly defined to stretch from the Liard River in British Columbia, down to the Rio Grande in New Mexico. The mountains can also be considered to run to Alaska or Mexico, but usually those mountains are considered to be part of the entire American cordillera, rather than part of the Rockies. The younger ranges of the Rocky Mountains uplifted during the late Cretaceous period (140 million-65 million years ago), although some portions of the southern mountains date from uplifts during the Precambrian (3,980 million-600 million years ago). The mountains' geology is a complex of igneous and metamorphic rock; younger sedimentary rock occurs along the margins of the southern Rocky Mountains, and volcanic rock from the Tertiary (65 million-1.8 million years ago) occurs in the San Juan Mountains and in other areas. Millennia of severe erosion in the Wyoming Basin transformed intermountain basins into a relatively flat terrain. The Tetons and other north-central ranges are magnificent granitic intrusions of folded and faulted rocks of Paleozoic and Mesozoic age (Peterson 1986; Knight 1994). Periods of glaciation occurred from the Pleistocene Epoch (1.8 million-70,000 years ago) to the Holocene Epoch (fewer than 11,000 years ago). Recent episodes included the Bull Lake Glaciation that began about 150,000 years ago and the Pinedale Glaciation that probably remained at full glaciation until 15,000-20,000 years ago (Pierce 1979). Ninety percent of Yellowstone National Park was covered by ice during the Pinedale Glaciation (Knight 1994). The "little ice age" was a period of glacial advance that lasted a few centuries from about 1550 to 1860. For example, the Agassiz and Jackson glaciers in Glacier National Park reached their most forward positions about 1860 during the little ice age (Grove 1990). Water in its many forms sculpted the present Rocky Mountain landscape (Athearn 1960). Runoff and snowmelt from the peaks feed Rocky Mountain rivers and lakes with the water supply for one-quarter of the United States. The rivers that flow from the Rocky Mountains eventually drain into three of the world's five Oceans: the Atlantic Ocean, the Pacific Ocean, and the Arctic Ocean. These rivers include: Arctic Ocean
- Arkansas River
- Athabasca River
- Colorado River
- Columbia River
- Fraser River
- Kootenay River
- Missouri River
- Peace River
- Platte River
- Rio Grande
- Saskatchewan River
- Snake River
- Yellowstone River The Continental Divide is located in the Rocky Mountains and designates the line at which waters flow either to the Atlantic or Pacific Oceans. Triple Divide Peak (8020 feet/2444 m) in Glacier National Park (US) is so named due to the fact that water which falls on the mountain reaches not only the Atlantic and Pacific, but the Arctic Ocean as well.

Human history

Since the last great Ice Age, the Rocky Mountains were a sacred home first to Paleo-Indians and then to the Native American tribes of the Apache, Arapaho, Bannock, Blackfoot, Cheyenne, Crow. Flathead, Shoshoni, Sioux, Ute, and others (Johnson 1994). Paleo-Indians hunted the now-extinct mammoth and ancient bison (an animal 20% larger than modern bison) in the foothills and valleys of the mountains. Like the modern tribes that followed them, Paleo-Indians probably migrated to the plains in fall and winter for bison and to the mountains in spring and summer for fish, deer, elk, roots, and berries. In Colorado, along the crest of the Continental Divide, rock walls that Native Americans built for driving game date back 5,400-5,800 years (Buchholtz 1983). A growing body of scientific evidence indicates that Native Americans had significant effects on mammal populations by hunting and on vegetation patterns through deliberate burning (Kay 1994). Recent human history of the Rocky Mountains is one of more rapid change (Lavender 1975; Knight 1994). The Spanish explorer Francisco Vásquez de Coronado--with a group of soldiers, missionaries, and African slaves--marched into the Rocky Mountain region from the south in 1540. The introduction of the horse, metal tools, rifles, new diseases, and different cultures profoundly changed the Native American cultures. Native American populations were extirpated from most of their historical ranges by disease, warfare, habitat loss (eradication of the bison), and continued assaults on their culture. The Lewis and Clark expedition (1804-1806) was the first scientific reconnaissance of the Rocky Mountains. Specimens were collected for contemporary botanists, zoologists, and geologists (Jackson 1962). The expedition was said to have paved the way to (and through) the Rocky Mountains for European-Americans from the East, although Lewis and Clark met at least 11 European-American mountain men during their travels. Mountain men, primarily French, Spanish, and British roamed the Rocky Mountains from 1720 to 1800 seeking mineral deposits and furs. After 1802, American fur traders and explorers ushered in the first widespread white presence in the Rockies. The more famous of these include Americans included William Henry Ashley, Jim Bridger, Kit Carson, John Colter, Thomas Fitzpatrick, Andrew Henry, and Jedediah Smith. On July 24, 1832, Benjamin Bonneville led the first wagon train across the Rocky Mountains by using Wyoming's South Pass. The Mormons began to settle near the Great Salt Lake in 1847. In 1859, gold was discovered near Cripple Creek, Colorado, and the regional economy of the Rocky Mountains was changed forever. The transcontinental railroad was completed in 1869, and Yellowstone National Park was established in 1872. While settlers filled the valleys and mining towns, conservation and preservation ethics began to take hold. President Harrison established several forest reserves in the Rocky Mountains in 1891-1892. In 1905, President Theodore Roosevelt extended the Medicine Bow Forest Reserve to include the area now managed as Rocky Mountain National Park (Buchholtz 1983). Economic development began to center on mining, forestry, agriculture, and recreation, as well as on the service industries that support them (Lavender 1975). Tents and camps became ranches and farms, forts and train stations became towns, and some towns became cities.

Industry and development

Economic resources of the Rocky Mountains are varied and abundant. Minerals found in the Rocky Mountains include significant deposits of copper, gold, lead, molybdenum, silver, tungsten, and zinc. The Wyoming Basin and several smaller areas contain significant reserves of coal, natural gas, oil shale, and petroleum. For example, the Climax mine, located near Leadville, Colorado, was the largest producer of Molybdenum in the world. Molybdenum is used in heat-resistant steel in such things as cars and planes. The Climax mine employed over 3,000 workers. The Coeur d’Alene mine of northern Idaho produces silver, lead, and zinc. Canada's largest coal mines are in the Crowsnest Coal Field near Sparwood, British Columbia and Elkford, British Columbia; additional coal mines exist near Hinton, Alberta. Abandoned mines with their wakes of mine tailings and toxic wastes dot the Rocky Mountain landscape. In one major example, eighty years of zinc mining profoundly polluted the river and bank near Eagle River in north-central Colorado. High concentrations of the metal carried by spring runoff harmed algae, moss, and trout populations. An economic analysis of mining effects at this site revealed declining property values, degraded water quality, and the loss of recreational opportunities. The analysis also revealed that cleanup of the river could yield $2.3 million in additional revenue from recreation. In 1983, the former owner of the zinc mine was sued by the Colorado Attorney General for the $4.8 million cleanup costs; 5 years later, ecological recovery was considerable (Brandt 1993). Agriculture and forestry are major industries. Agriculture includes dryland and irrigated farming and livestock grazing. Livestock are frequently moved between high-elevation summer pastures and low-elevation winter pastures. Human population is not very dense in the Rocky Mountains, with an average of four people per square kilometer (10 per square mile) and few cities with over 50,000 people. However, the human population grew rapidly in the Rocky Mountain states between 1950 and 1990. The 40-year statewide increases in population range from 35% in Montana to about 150% in Utah and Colorado. The populations of several mountain towns and communities have doubled in the last 40 years. Jackson Hole, Wyoming, increased 260%, from 1,244 to 4,472 residents, in 40 years.

Tourism

Every year the scenic areas and recreational opportunities of the Rocky Mountains draw millions of tourists. The main language of the Rocky Mountains is English. But there are also linguistic pockets of Spanish and Native American languages. People from all over the world visit the sites to hike, camp, or engage in mountain sports. In the summer, main tourist attractions are Native American
- Pikes Peak
- Royal Gorge
- Rocky Mountain National Park
- Yellowstone National Park
- Grand Teton National Park
- Glacier National Park (U.S.) Canadian National Parks in the mountain range are
- Banff National Park
- Glacier National Park (Canada)
- Jasper National Park
- Kootenay National Park
- Mount Revelstoke National Park
- Waterton Lakes National Park
- Yoho National Park Glacier National Park (U.S.) and Waterton Lakes National Park border each other on the U.S./Canadian border and collectively are known as the Waterton-Glacier International Peace Park. (See also International Peace Park.) In the winter, skiing is the main attraction. The major ski resorts are: skiing
- Colorado:
- Aspen
- Vail
- Keystone
- Breckenridge
- Utah:
- Alta
- Snowbird
- Park City
- Sun Valley, Idaho
- Montana:
- Big Mountain
- Big Sky
- Alberta:
- Lake Louise
- Sunshine Village
- Fernie, British Columbia The adjacent Columbia Mountains in British Columbia and Idaho contain major resorts such as Schweitzer, Panorama and Kicking Horse. See also: List of U.S. Rocky Mountain ski resorts, List of Alberta ski resorts, List of B.C. ski resorts

Climate

List of B.C. ski resorts The Rocky Mountains have a highland climate. The average temperature in the Rockies per year is 43 °F (6 °C). July is the hottest month with an average temperature of 82 °F (28 °C). In January, the average monthly temperature is 7 °F (−14 °C), making it the coldest month in the Rockies. The average precipitation per year is approximately 14 inches (360 mm). The summers in the Rockies are warm and dry, because the western fronts impede the advancing of water-carrying storm systems. The average temperature in summer is 59 °F (15 °C) and the average precipitation is 5.9 inches (150 mm). Winter is usually wet and very cold, with an average temperature of 28 °F (−2 °C) and average snowfall of 11.4 inches (29.0 cm). In spring, the average temperature is 40 °F (4 °C) and the average precipitation is 4.2 inches (107 mm). And in the fall, the average precipitation is 2.6 inches (66 mm) and the average temperature is 44 °F (7 °C).

References

- Athearn, R. G. 1960. High country empire: the High Plains and Rocky Mountains. McGraw-Hill, New York. 358 pp.
- Brandt, E. 1993. How much is a gray wolf worth? National Wildlife 31:412.
- Buchholtz, C. W. 1983. Rocky Mountain National Park: a history. Colorado Associated University Press, Boulder. 255 pp.
- Grove, J. M. 1990. The little ice age. Rutledge Press, New York. 498 pp.
- Jackson, D. 1962. Letters of the Lewis and Clark expedition with related documents 17831854. University of Illinois Press, Urbana. 728 pp.
- Kay, C. E. 1994. Aboriginal overkill. Human Nature 5:359398.
- Lavender, D. 1975. The Rockies. Harper and Row, New York. 433 pp.
- Knight, D. H. 1994. Mountains and plains: the ecology of Wyoming landscapes. Yale University Press, New Haven, Conn. 338 pp.
- Peterson, J. A., editor. 1986. Paleotectonics and sedimentation in the Rocky Mountain Region, United States. Memoir 41, American Association of Petroleum Geologists. Tulsa, Okla. 693 pp.
- Pierce, K. L. 1979. History and dynamics of glaciation in the northern Yellowstone National Park area. Professional Paper 729-F. U.S. Geological Survey, Washington, D.C. 90 pp

External links

- [http://biology.usgs.gov/s+t/SNT/noframe/wm146.htm USGS Biology web site about Rocky Mountains] (public domain source)]
- [http://wrgis.wr.usgs.gov/docs/parks/province/rockymtn.html U.S. Geological Survey website on the Rocky Mountains]
- [http://www.blueplanetbiomes.org/rocky_mountain.htm Blue Planet Biomes - Rocky Mountains]
- [http://www.nationalparksgallery.com/parks/Rocky-Mountain-National-Park Rocky Mountain National Park] - National Parks Gallery Category:Mountain ranges of Canada Category:Mountain ranges of the United States zh-min-nan:Rocky Soaⁿ-lêng ja:ロッキー山脈 th:เทือกเขาร็อกกี

Yellowstone National Park

: For the next-generation airliner series from Boeing, see Boeing Yellowstone. Yellowstone National Park is a U.S. National Park located in the states of Wyoming, Montana, and Idaho. Yellowstone is the first and oldest national park in the world and covers 3,470 square miles (8,980 km²), mostly in the northwest corner of Wyoming. The park is famous for its various geysers, hot springs, and other geothermal features and is home to grizzly bears and wolves, and free-ranging herds of bison and elk. It is the core of the Greater Yellowstone Ecosystem, one of the largest intact temperate zone ecosystems remaining on the planet. Long before any recorded human history in Yellowstone, a massive volcanic eruption spewed an immense volume of ash that covered all of the western U.S., much of the Midwest, northern Mexico and some areas of the eastern Pacific Coast. The eruption dwarfed that of Mount St. Helens in 1980 and left a huge caldera 43 miles by 18 miles (70 km by 30 km) sitting over a huge magma chamber (see Geology section and Yellowstone Caldera). Yellowstone has registered three major eruption events in the last 2.2 million years with the last event occurring 640,000 years ago. Its eruptions are the largest known to have occurred on Earth within that timeframe, producing drastic climate change in the aftermath. The park was named for the yellow rocks seen in the Grand Canyon of the Yellowstone—a deep gash in the Yellowstone Plateau that was formed by floods during previous ice ages and by river erosion from the Yellowstone River.

Human history

The human history of the park dates back 12,000 years. It was known to the original natives as "Mitzi-a-dazi," the "River of Yellow Rocks," because of the hydrothermally altered iron-containing yellow rocks in the Grand Canyon of the Yellowstone (many people incorrectly believe that the yellow color is from sulfur). The Native Americans that hunted and fished in the Yellowstone region also utilized the significant amounts of obsidian found in the park to make cutting tools and weapons. In fact, arrowheads made of Yellowstone obsidian have been found as far away as the Mississippi Valley, which strongly indicate that a regular obsidian trade existed between Yellowstone Native Americans and tribes further east. obsidian trade In 1806 a member of the Lewis and Clark Expedition named John Colter left the Expedition to join a group of fur trappers and was probably the first non-Native American to visit the region and make contact with the Native Americans there. After surviving wounds he suffered in a battle with Crow and Blackfoot tribes, he gave a description of a place of "fire and brimstone" that was dismissed by most people as delirium. The supposedly imaginary place was nicknamed "Colter's Hell." Mountain man Jim Bridger later returned from an 1857 expedition to the park's area and told tales of boiling springs, spouting water, a mountain of glass and yellow rock. These reports were largely ignored, however, because Bridger was known for being a "spinner of yarns." Nonetheless his stories did arouse the interest of explorer and geologist F.V. Hayden who in 1859 started a two-year survey of the upper Missouri River region with Bridger as a guide and with United States Army surveyor W.F. Raynolds. The party was able to reach the approaches to the Yellowstone region but was not able to go any further due to heavy snows. The intervening American Civil War stopped all attempts to explore the region, and Hayden would not be able to fulfill his mission to explore the area for another 11 years. American Civil War A party of Montanans then organized the Washburn-Langford-Doane Expedition, headed by the surveyor-general of Montana Henry Washburn. Amongst the group was Nathaniel P. Langford, who would later become known as "National Park" Langford, and an Army detachment commanded by Lt. Gustavus Doane. The expedition spent about a month in 1870 exploring the region, collecting specimens and naming sites of interest. In 1871 Hayden led a second, larger expedition, which was now government sponsored, to the Yellowstone region. He compiled a comprehensive report on Yellowstone which included large-format photographs by William Henry Jackson and paintings by Thomas Moran. This report helped to convince the U.S. Congress to withdraw this region from public auction. Then on March 1, 1872, President Ulysses S. Grant signed a bill into law that created Yellowstone National Park. Langford then served for five years without pay as the first superintendent of the park and was followed by several other superintendents (who worked with some minimal funding). The second superintendent was Philetus Norris who essentially volunteered for the position, after traveling through Yellowstone and witnessing its problems first hand. During his tenure Congress finally began to give the superintendent a salary and minimal funds to operate the park. He used these monies to expand access to and further explore Yellowstone. Norris also hired Harry Yount (nicknamed "Rocky Mountain Harry") to control poaching and vandalism in the park. Today, Harry Yount is considered the very first national park ranger. Harry Yount Three additional superintendents followed, but none proved effective in stopping the destruction of Yellowstone's natural resources. This continued until 1886 when the Army was given the task of managing the park (see Fort Yellowstone). The Army remained the steward of the park until control was given to a civilian corps of rangers under the newly created National Park Service in 1916. More recently, Yellowstone has been designated as an International Biosphere Reserve on October 26, 1976, and a United Nations World Heritage Site on September 8, 1978.

Forest fires

1978 A series of lightning-derived fires started to burn large portions of the park in July of the especially dry summer of 1988. Thousands of firefighters responded to the blaze in order to prevent human-built structures from succumbing to the flames. Controversially, however, no serious effort was made to completely extinguish the fires, and they burned until the arrival of autumn rains. Ecologists argued that fire is part of the Yellowstone ecosystem and that not allowing the fires to run their course (as has been the practice in the past) will result in a choked, sick and decaying forest. In fact, relatively few megafauna in the park were killed by the fires and since the blaze many saplings have sprung up on their own, old vistas were viewable once again and many previously unknown archaeological and geological sites of interest were found and cataloged by scientists. The National Park Service now has a policy of lighting smaller, controlled "prescribed fires" to prevent another dangerous buildup of flammable materials.

Geography

The continental divide of North America runs roughly diagonally through the southwestern part of the park. The divide is a topographic ridgeline that bisects the continent between Pacific Ocean and Atlantic Ocean water drainages (the drainage from one-third of the park is on the Pacific side of this divide). Atlantic Ocean For example, the Yellowstone River and the Snake River both have their origin close to each other in the park. However, the headwaters of the Snake River are on the west side of the continental divide, and the headwaters of the Yellowstone River are on the east side of that divide. The result is that the waters of the Snake River head toward the Pacific Ocean, and the waters of the Yellowstone head for the Atlantic Ocean (via the Gulf of Mexico). The park sits on a high plateau which is, on average, 8,000 feet (2,400 m) above sea level and is bounded on nearly all sides by mountain ranges of the Middle Rocky Mountains, which range from 10,000 to 14,000 feet (3,000 to 4,300 m) in elevation. These ranges are: the Gallatin Range (to the northwest), Beartooth Mountains (to the north), Absaroka Mountains (to the east), Wind River Range (southeast corner), Teton Mountains (to the south, see Grand Teton National Park) and the Madison Range (to the west). The most prominent summit in the plateau is Mount Washburn at 10,243 feet (3,122 m). Just outside of the southwestern park border is the Island Park Caldera, which is a plateau ringed by low hills. Beyond that is the Snake River Plains of southern Idaho, which are covered by flood basalts and slope gently to the southwest (see Craters of the Moon National Monument). The major feature of the Yellowstone Plateau is the Yellowstone Caldera; a very large caldera which has been nearly filled-in with volcanic debris and measures 50 by 60 kilometers (30 by 40 mi). Within this caldera lies most of Yellowstone Lake, which is the largest high-elevation lake in North America, and two resurgent domes, which are areas that are uplifting at a slightly faster rate than the rest of the plateau.

Geology

See also Geothermal areas of Yellowstone Geothermal areas of Yellowstone Geothermal areas of Yellowstone Yellowstone is at the northeast tip of a smooth U-shaped curve through the mountains, which is now the Snake River Plain. This curved plain was created as the North American continent drifted across a stationary volcanic hotspot beneath the Earth's crust. This hot spot used to be near what is now Boise, Idaho, but North America has drifted at a rate of 45 mm a year in a southwestern direction, shifting the hot spot to its present location. Yellowstone Caldera is the largest volcanic system in North America. It has been termed a "supervolcano" because the caldera was formed by exceptionally large explosive eruptions. It was created by a cataclysmic eruption that occurred 640,000 years ago that released 1,000 cubic kilometers of ash, rock and pyroclastic materials (this was 800 times larger than Mount St. Helens' 1980 eruption), forming a crater nearly a kilometre deep and 40 by 70 kilometres in area (25 by 45 mi) (the size of the caldera has been modified a bit since this time and has mostly been filled in, however). The welded tuff geologic formation created by this eruption is called the Lava Creek Tuff. In addition to the last great eruptive cycle there were two other previous ones in the Yellowstone area. Each eruption is in fact a part of an eruptive cycle that climaxes with the collapse of the roof of a partially emptied magma chamber. This creates a crater, called a caldera, and releases vast amounts of volcanic material (usually through fissures that ring the caldera). The time between the last three cataclysmic eruptions in the Yellowstone area has ranged from 600,000 to 900,000 years, but the small number of such climax eruptions can not be used to make a prediction for the time range for the next climax eruption. The first and largest eruption climaxed to the southwest of the current park boundaries 2.2 million years ago and formed a caldera about 50 by 80 kilometres in area (30 by 50 mi) and hundreds of meters deep after releasing 2,500 cubic kilometers of material (mostly ash, pumice and other pyroclastics). pumice This caldera has been filled in by subsequent eruptions, and the geologic formation created by this eruption is called the Huckleberry Ridge Tuff. Huckleberry Ridge Tuff] The second eruption, at 280 km³ of material ejected, climaxed 1.2 million years ago and formed the much smaller Island Park Caldera and the geologic formation called the Mesa Falls Tuff. All three climax eruptions released vast amounts of ash that blanketed much of central North America and fell many hundreds of miles away (as far as California to the southwest; see Lake Tecopa). The amount of ash and gases released into the atmosphere probably caused significant impacts to world weather patterns and led to the extinction of many species in at least North America. About 160,000 years ago a much smaller climax eruption occurred which formed a relatively small caldera that is now filled in with the West Thumb of Yellowstone Lake. Yellowstone Lake Lava strata is most easily seen at the Grand Canyon of the Yellowstone where the Yellowstone River continues to carve into the ancient lava flows. According to Ken Pierce, U.S. Geological Survey geologist, at the end of the last glacial period, about 14,000 to 18,000 years ago, ice dams formed at the mouth of Yellowstone Lake. When the ice dams melted, a great volume of water was released downstream causing massive flash floods and immediate and catastrophic erosion of the present-day canyon. These flash floods probably happened more than once. The canyon is a classic V-shaped valley, indicative of river-type erosion rather than glaciation. Today the canyon is still being eroded by the Yellowstone River. valley After the last major climax eruption 630,000 years ago until about 70,000 years ago, Yellowstone Caldera was nearly filled in with periodic eruptions of rhyolitic lavas (example at Obsidian Cliffs) and basaltic lavas (example at Sheepeaters Cliff). But 150,000 years ago the floor of the plateau began to bulge up again. Two areas in particular at the foci of the elliptically shaped caldera are rising faster than the rest of the plateau. This differential in uplift has created two resurgent domes (Sour Creek dome and Mallard Lake dome) which are uplifting at 15 millimeters a year while the rest of the caldera area of the plateau is uplifting at 12.5 millimeters a year. Preserved within Yellowstone are many geothermal features and some 10,000 hot springs and geysers, 62% of the planet's known total. The superheated water that sustains these features comes from the same hot spot described above. The most famous geyser in the park, and perhaps the world, is Old Faithful Geyser (located in Upper Geyser Basin), but the park also contains the largest active geyser in the world, Steamboat Geyser in the Norris Geyser Basin..
Steamboat Geyser In 2003 changes at the Norris Geyser Basin resulted in the temporary closure of some trails in the basin. This coincided with the release of reports about a multiple year USGS research project mapping the bottom of Yellowstone Lake that identified a structural dome that had uplifted at some time in past beneath Yellowstone Lake. On March 10, 2004, a biologist discovered 5 dead bison which apparently had inhaled toxic geothermal gases trapped in the Norris Geyser Basin by a seasonal atmospheric inversion. Shortly after in April 2004 the park experienced an upsurge of earthquake activity. These events inspired a great deal of media attention and speculation about the geologic future of the region. The United States government responded by allocating more resources to monitor the volcano and reminding visitors to remain on designated safe trails.

Biology and ecology

Main articles: Animals of Yellowstone, Greater Yellowstone Ecosystem The dominant tree species in the park is Lodgepole pine, however, varieties of spruce, fir and aspen are also common. There are at least 600 species of trees and plants found in the park, some of which are found nowhere else. Yellowstone is widely considered to be the finest megafauna wildlife habitats in the lower 48 states. Animals found in the park include the majestic American bison (buffalo), grizzly bear, black bear, elk, moose, mule deer, pronghorn, wolverine, bighorn sheep and mountain lion (puma). The Yellowstone Lake Cutthroat Trout is a highly sought after trophy fish by anglers yet has been threatened in recent years by the suspicious introduction of lake trout that compete for spawning grounds and are known to consume smaller cutthroat trout. cutthroat trout The relatively large bison populations that exist in the park are a concern for ranchers who fear that the bison can transmit bovine diseases to their domesticated cousins. In fact, about half of Yellowstone's bison have been exposed to brucellosis, a bacterial disease that came to North America with European cattle and may cause cattle to miscarry. The disease has little effect on park bison and no reported case of transmission from wild bison to a visitor or to domestic livestock has ever been filed. But since the possibility of contagion still exists, the State of Montana believes its "brucellosis-free" status may be jeopardized if bison are in proximity to cattle. Montana has approved a bison hunt for fall of 2005, with 50 licenses issued to shoot bison that have left the park. Elk also carry the disease, but this popular game species is not considered a threat to livestock. Elk To combat the perceived threat, National Park personnel regularly harass bison herds back into the park when they venture outside of park borders. Animal rights activists state that is a cruel practice and that the possibility for disease transmission is not as great as some ranchers maintain. Ecologists also point out that the bison are just traveling to seasonal grazing areas that lie within the Greater Yellowstone Ecosystem that have been converted to cattle grazing (most of these areas are also within United States National Forests). United States National Forests A controversial decision by the U.S. Fish and Wildlife Service (which oversees threatened and endangered species), is the recent reintroduction of wolves into the park's ecosystem. For many years the wolves were hunted and harassed until they become locally extinct in the 1930s. The smaller cousin of the wolf, the coyote, then became the park's top predator. However, the coyote is not able to bring down any large animal in the park and the result of this lack of a top predator on these populations was a marked increase in lame and sick megafauna. Since the reintroduction of wolves in the late 1990s this trend has started to reverse. coyote However, ranchers in surrounding areas are concerned about wolves that venture outside the park and prey on their livestock, especially sheep and cattle. For the most part, wolves kill what they were taught to kill as pups, so they tend to prey on elk rather t