Government
Federal republic.
The president is elected for a four-year term and may be reelected only once. The bicameral Congress consists of the 100-member Senate, elected to a six-year term with one-third of the seats becoming vacant every two years, and the 435-member House of Representatives, elected every two years. The minimum voting age is 18.
United States, officially United States of America, republic (2005 est. pop. 295,734,000), 3,539,227 sq mi (9,166,598 sq km), North America. The United States is the world's third largest country in population and in area. It consists of 50 states and a federal district. The conterminous (excluding Alaska and Hawaii) United States stretches across central North America from the Atlantic Ocean on the east to the Pacific Ocean on the west, and from Canada on the north to Mexico and the Gulf of Mexico on the south. The state of Alaska is located in extreme NW North America between the Arctic and Pacific oceans and is bordered by Canada on the east. The state of Hawaii, an island chain, is situated in the E central Pacific Ocean c.2,100 mi (3,400 km) SW of San Francisco. Washington, D.C., is the capital of the United States, and New York is its largest city.
The outlying territories and areas of the United States include: in the Caribbean Basin, Puerto Rico (a commonwealth associated with the United States) and the Virgin Islands of the United States (purchased from Denmark in 1917); in the Pacific Ocean, Guam (ceded by Spain after the Spanish-American War), the Northern Mariana Islands (a commonwealth associated with the United States), American Samoa, Wake Island, and several other islands. The United States also has compacts of free association with the Republic of the Marshall Islands, the Republic of Palau, and the Federated States of Micronesia.
Political Geography
The conterminous United States may be divided into several regions: the New England states (Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, and Connecticut), the Middle Atlantic states (New York, New Jersey, Pennsylvania, Delaware, Maryland, Virginia, and West Virginia), the Southeastern states (North Carolina, South Carolina, Georgia, Florida, Alabama, Mississippi, Louisiana, Arkansas, Tennessee, and Kentucky), the states of the Midwest (Ohio, Indiana, Illinois, Michigan, Wisconsin, Minnesota, Iowa, and Missouri), the Great Plains states (North Dakota, South Dakota, Nebraska, and Kansas), the Mountain states (Montana, Idaho, Wyoming, Colorado, and Utah), the Southwestern states (Oklahoma, Texas, New Mexico, and Arizona), and the states of the Far West (Washington, Oregon, California, and Nevada).
Alaska is the largest state in area (656,424 sq mi/1,700,578 sq km), and Rhode Island is the smallest (1,545 sq mi/4,003 sq km). California has the largest population (2000 pop. 33,871,648), while Wyoming has the fewest people (2000 pop. 493,782). In the late 20th cent., Nevada, Arizona, Florida, Colorado, Utah, Georgia, and Texas experienced the fastest rates of population growth, while California, Texas, Florida, Georgia, Arizona, and North Carolina gained the greatest number of residents. West Virginia, North Dakota, and the District of Columbia experienced population decreases over the same period. The largest U.S. cities are New York, Los Angeles, Chicago, Houston, and Philadelphia. Among the other major cities are Boston, Pittsburgh, Baltimore, Washington, D.C., Richmond, Virginia Beach, Charlotte, Atlanta, Jacksonville, Tampa, Miami, Cleveland, Columbus, Cincinnati, Detroit, Indianapolis, Milwaukee, Minneapolis, Saint Louis, Nashville, Memphis, New Orleans, Kansas City, Oklahoma City, Dallas–Fort Worth, Austin, San Antonio, El Paso, Albuquerque, Denver, Salt Lake City, Phoenix, Tucson, Las Vegas, Seattle, Portland, Sacramento, San Francisco, San Jose, Fresno, Long Beach, San Diego, and Honolulu.
Physical Geography
The conterminous United States may be divided into seven broad physiographic divisions: from east to west, the Atlantic–Gulf Coastal Plain; the Appalachian Highlands; the Interior Plains; the Interior Highlands; the Rocky Mountain System; the Intermontane Region; and the Pacific Mountain System. An eighth division, the Laurentian Uplands, a part of the Canadian Shield, dips into the United States from Canada in the Great Lakes region. It is an area of little local relief, with an irregular drainage system and many lakes, as well as some of the oldest exposed rocks in the United States.
The terrain of the N United States was formed by the great continental ice sheets that covered N North America during the late Cenozoic Era. The southern edge of the ice sheet is roughly traced by a line of terminal moraines extending west from E Long Island and then along the course of the Ohio and Missouri rivers to the Rocky Mts.; land north of this line is covered by glacial material. Alaska and the mountains of NW United States had extensive mountain glaciers and were heavily eroded. Large glacial lakes (see Lake Bonneville under Bonneville Salt Flats; Lahontan, Lake) occupied sections of the Basin and Range province; the Great Salt Lake and the other lakes of this region are remnants of the glacial lakes.
The East and the Gulf Coast
The Atlantic–Gulf Coastal Plain extends along the east and southeast coasts of the United States from E Long Island to the Rio Grande; Cape Cod and the islands off SE Massachusetts are also part of this region. Although narrow in the north, the Atlantic Coastal Plain widens in the south, merging with the Gulf Coastal Plain in Florida. The Atlantic and Gulf coasts are essentially coastlines of submergence, with numerous estuaries, embayments, islands, sandspits, and barrier beaches backed by lagoons. The northeast coast has many fine natural harbors, such as those of New York Bay and Chesapeake Bay, but south of the great capes of the North Carolina coast (Fear, Lookout, and Hatteras) there are few large bays. A principal feature of the lagoon-lined Gulf Coast is the great delta of the Mississippi River.
The Atlantic Coastal Plain rises in the west to the rolling Piedmont (the falls along which were an early source of waterpower), a hilly transitional zone leading to the Appalachian Mountains. These ancient mountains, a once towering system now worn low by erosion, extend southwest from SE Canada to the Gulf Coastal Plain in Alabama. In E New England, the Appalachians extend in a few places to the Atlantic Ocean, contributing to a rocky, irregular coastline. The Appalachians and the Adirondack Mountains of New York (which are geologically related to the Canadian Shield) include all the chief highlands of E United States; Mt. Mitchell (6,684 ft/2,037 m high), in the Black Mts. of North Carolina, is the highest point of E North America.
The Plains and Highlands of the Interior
Extending more than 1,000 mi (1,610 km) from the Appalachians to the Rocky Mts. and lying between Canada (into which they extend) in the north and the Gulf Coastal Plain in the south are the undulating Interior Plains. Once covered by a great inland sea, the Interior Plains are underlain by sedimentary rock. Almost all of the region is drained by one of the world's greatest river systems—the Mississippi-Missouri. The Interior Plains may be divided into two sections: the fertile central lowlands, the agricultural heartland of the United States; and the Great Plains, a treeless plateau that gently rises from the central lowlands to the foothills of the Rocky Mts. The Black Hills of South Dakota form the region's only upland area.
The Interior Highlands are located just W of the Mississippi River between the Interior Plains and the Gulf Coastal Plain. This region consists of the rolling Ozark Plateau (see Ozarks) to the north and the Ouachita Mountains, which are similar in structure to the ridge and valley section of the Appalachians, to the east.
The Western Mountains and Great Basin
West of the Great Plains are the lofty Rocky Mountains. This geologically young and complex system extends into NW United States from Canada and runs S into New Mexico. There are numerous high peaks in the Rockies; the highest is Mt. Elbert (14,433 ft/4,399 m). The Rocky Mts. are divided into four sections—the Northern Rockies, the Middle Rockies, the Wyoming (Great Divide) Basin, and the Southern Rockies. Along the crest of the Rockies is the Continental Divide, separating Atlantic-bound drainage from that heading for the Pacific Ocean.
Between the Rocky Mts. and the ranges to the west is the Intermontane Region, an arid expanse of plateaus, basins, and ranges. The Columbia Plateau, in the north of the region, was formed by volcanic lava and is drained by the Columbia River and its tributary the Snake River, both of which have cut deep canyons into the plateau. The enormous Colorado Plateau, an area of sedimentary rock, is drained by the Colorado River and its tributaries; there the Colorado River has entrenched itself to form the Grand Canyon, one of the world's most impressive scenic wonders. West of the plateaus is the Basin and Range province, an area of extensive semidesert.
The lowest point in North America, in Death Valley (282 ft/86 m below sea level), is there. The largest basin in the region is the Great Basin, an area of interior drainage (the Humboldt River is the largest stream) and of numerous salt lakes, including the Great Salt Lake. Between the Intermontane Region and the Pacific Ocean is the Pacific Mountain System, a series of ranges generally paralleling the coast, formed by faulting and volcanism. The Cascade Range, with its numerous volcanic peaks extends S from SW Canada into N California, and from there is continued south by the Sierra Nevada, a great fault block. Mt. Whitney (14,495 ft/4,418 m), in the Sierra Nevada, is the highest peak in the conterminous United States.
The Pacific Coast, Alaska, and Hawaii
West of the Cascades and the Sierra Nevada and separated from them by a structural trough are the Coast Ranges, which extend along the length of the U.S. Pacific coast. The Central Valley in California, the Willamette Valley in Oregon, and the Puget Sound lowlands in Washington are part of the trough. The San Andreas Fault, a fracture in the earth's crust, parallels the trend of the Coast Ranges from San Francisco Bay SE to NW Mexico; earthquakes are common along its entire length. The Pacific Coastal Plain is narrow, and in many cases the mountains plunge directly into the sea. A coastline of emergence, it has few islands, except for the Channel Islands (see Santa Barbara Islands) and those in Puget Sound; there are few good harbors besides Puget Sound, San Francisco Bay, and San Diego Bay.
Alaska may be divided into four physiographic regions; they are, from north to south, the Arctic Lowlands, the coastal plain of the Arctic Ocean; the Rocky Mountain System, of which the Brooks Range is the northernmost section; the Central Basins and Highlands Region, which is dominated by the Yukon River basin; and the Pacific Mountain System, which parallels Alaska's southern coast and which rises to Mt. McKinley (Denali; 20,320 ft/6,194 m), the highest peak of North America. The islands of SE Alaska and those of the Aleutian Islands chain are partially submerged portions of the Pacific Mountain System and are frequently subjected to volcanic activity and earthquakes. These islands, like those of Hawaii, are the tops of volcanoes that rise from the floor of the Pacific Ocean. Mauna Kea and Mauna Loa on Hawaii are active volcanoes; the other Hawaiian islands are extinct volcanoes.
Major Rivers and Lakes
The United States has an extensive inland waterway system, much of which has been
improved for navigation and flood control and developed to produce hydroelectricity and irrigation water by such agencies as the U.S. Bureau of Reclamation, the U.S. Army Corps of Engineers, and the Tennessee Valley Authority. Some of the world's larger dams, man-made lakes, and hydroelectric power plants are on U.S. rivers. The Mississippi-Missouri river system (c.3,890 mi/6,300 km long), is the longest in the United States and the second longest in the world. With its hundreds of tributaries, chief among which are the Red River, the Ohio, and the Arkansas, the Mississippi basin drains more than half of the nation. The Yukon, Columbia, Colorado, and Rio Grande also have huge drainage basins. Other notable river systems include the Connecticut, Hudson, Delaware, Susquehanna, Potomac, James, Alabama, Trinity, San Joaquin, and Sacramento.
The Great Salt Lake and Alaska's Iliamna are the largest U.S. lakes outside the Great Lakes and Lake of the Woods, which are shared with Canada (Lake Michigan and Iliamna are the largest freshwater lakes entirely within the United States). The Illinois Waterway connects the Great Lakes with the Mississippi River, and the New York State Canal System links them with the Hudson. The Intracoastal Waterway provides sheltered passage for shallow draft vessels along the Atlantic and Gulf Coasts.
Climate
The United States has a broad range of climates, varying from the tropical rain-forest of Hawaii and the tropical savanna of S Florida (where the Everglades are found) to the subarctic and tundra climates of Alaska. East of the 100th meridian (the general dividing line between the dry and humid climates) are the humid subtropical climate of SE United States and the humid continental climate of NE United States. Extensive forests are found in both these regions. West of the 100th meridian are the steppe climate and the grasslands of the Great Plains; trees are found along the water courses.
In the SW United States are the deserts of the basin and range province, with the hottest and driest spots in the United States. Along the Pacific coast are the Mediterranean-type climate of S California and, extending north into SE Alaska, the marine West Coast climate. The Pacific Northwest is one of the wettest parts of the United States and is densely forested. The Rocky Mts., Cascades, and Sierra Nevada have typical highland climates and are also heavily forested. In addition to the Grand Canyon in Arizona and Great Salt Lake in Utah, widely publicized geographic marvels of the United States include Niagara Falls, on the New York–Canada border; the pink cliffs of Bryce Canyon National Park, in Utah; and the geysers of Yellowstone National Park, primarily in Wyoming (for others, see National Parks and Monuments, table).
People
More than 79% of the United States population are urban (and more than 50% are estimated to be suburban, a not strictly defined category that can be taken as a subset of urban), and the great majority of the inhabitants are of European descent. According to the U.S. census, as of 2000 the largest minority were Hispanics, who, at 35,305,818 people, accounted for 12.5% of the population; this figure includes people of Mexican, Puerto Rican, Cuban, and many other origins (who may be any race). The African-American population numbered 34,658,190, or 12.3% of the population, although an additional 0.6% of the population were of African-American descent in part. The Asian population totaled 10,242,998 in 2000, or 3.6%, and consisted predominantly of people of Chinese, Filipino, Indian, Vietnamese, Korean, or Japanese origin; an additional 0.6% of the population had a mixed-race background that was partially Asian. The Native American population of the United States, which included natives of Alaska such as Eskimos and Aleuts, was 2,475,956, or 0.9%, but an additional 0.6% were of partial Native American descent. Roughly a third of Native Americans lived on reservations, trust lands, territories, or other lands under Native American jurisdiction. Hawaiians and other Pacific Islanders numbered 398,835 in 2000, or 0.1% of the population; an additional 0.2% were of partial Pacific Island descent. Persons who defined themselves as being of mixed racial background constituted 2.4% of the population in 2000, but the number of people with a mixed racial background, especially in the African-American and Hispanic populations, was in fact much higher. About 82% of the people speak English and about 11% speak Spanish as their first language. There are large numbers of speakers of many other Indo-European and Asian languages, and most languages of the world are spoken somewhere in the United States.
In addition to the original group of British settlers in the colonies of the Atlantic coast, numerous other national groups were introduced by immigration. Large numbers of Africans were transported in chains under abysmal conditions to work as slaves, chiefly on the plantations of the South. When the United States was developing rapidly with the settlement of the West (where some earlier groups of French and Spanish settlers were absorbed), immigrants from Europe poured into the land. An important early group was the Scotch-Irish. Just before the middle of the 19th cent., Irish and German immigrants were predominant. A little later the Scandinavian nations supplied many settlers.
After the Civil War, the immigrants came mainly from the nations of S and E Europe: from Italy, Greece, Russia, the part of Poland then in Russia, and from Austria-Hungary and the Balkans. During this period, there were also large numbers of immigrants from China. During the peak years of immigration between 1890 and 1924 more than 15 million immigrants arrived in the United States. After the immigration law of 1924 (see immigration), immigration was heavily restricted until the mid-1960s. Since the 1980s, large numbers of new immigrants have arrived. U.S. Census Bureau figures indicate that the proportion of foreign-born people in the U.S. population reached 11.1% in 2000, the highest it had been since the 1930 census; more than 40% of the more than 31 million foreign born had arrived since 1990. More than half of all foreign-born persons in the United States are from Latin America, and more than a quarter are from Asia.
Religion and Education
There is religious freedom in the United States, and the overwhelming majority of
Americans are Christians. In turn, the majority of Christians are Protestants, but of many denominations. The largest single Christian group embraces members (some 61 million in 1999) of the Roman Catholic Church; the Orthodox Eastern Church is also represented. In addition, roughly 2.5% of Americans adhere to Judaism, and some 1%–2% are Muslims. Education in the United States is administered chiefly by the states. Each of the 50 states has a free and public primary and secondary school system. There are also in the United States more than 3,500 institutions of higher learning, both privately supported and state supported (see separate articles on individual colleges and universities).
Economy
The mineral and agricultural resources of the United States are tremendous. Although the country was virtually self-sufficient in the past, increasing consumption, especially of energy, continues to make it dependent on certain imports. It is, nevertheless, the world's largest producer of both electrical and nuclear energy. It leads all nations in the production of liquid natural gas, aluminum, sulfur, phosphates, and salt. It is also a leading producer of copper, gold, coal, crude oil, nitrogen, iron ore, silver, uranium, lead, zinc, mica, molybdenum, and magnesium. Although its output has declined, the United States is among the world leaders in the production of pig iron and ferroalloys, steel, motor vehicles, and synthetic rubber. Agriculturally, the United States is first in the production of cheese, corn, soybeans, and tobacco. The United States is also one of the largest producers of cattle, hogs, cow's milk, butter, cotton, oats, wheat, barley, and sugar; it is the world's leading exporter of wheat and corn and ranks third in rice exports. In 1995, U.S. fisheries ranked fifth in the world in total production.
Major U.S. exports include aircraft, motor vehicles and parts, food, iron and steel products, electric and electronic equipment, industrial and power-generating machinery, organic chemicals, transistors, telecommunications equipment, pharmaceuticals, and consumer goods. Leading imports include ores and metal scraps, petroleum and petroleum products, machinery, transportation equipment (especially automobiles), food, clothing, computers, and paper and paper products. The major U.S. trading partners are Canada (in the world's largest bilateral trade relationship), Mexico, China, Japan, Great Britain, Germany, and South Korea. Despite the steady growth in imports, the gross domestic product also has continued to rise, and in 2006 it was easily the largest in the world at about $13 trillion. The development of the economy has been spurred by the growth of a complex network of communications not only by railroad, highways, inland waterways, and air but also by telephone, radio, television, computer (including the Internet), and fax machine. This infrastructure has fostered not only agricultural and manufacturing growth but has also contributed to the leading position the United States holds in world tourism revenues and to the ongoing shift to a service-based economy. In 1996 some 74% of Americans worked in service industries, a proportion matched, among major economic powers, only by Canada.
Government
The government of the United States is that of a federal republic set up by the Constitution of the United States, adopted by the Constitutional Convention of 1787. There is a division of powers between the federal government and the state governments. The federal government consists of three branches: the executive, the legislative, and the judicial. The executive power is vested in the President and, in the event of the President's incapacity, the Vice President. (For a chronological list of all the presidents and vice presidents of the United States, including their terms in office and political parties, see the table entitled Presidents of the United States.) The executive conducts the administrative business of the nation with the aid of a cabinet composed of the Attorney General and the Secretaries of the Departments of State; Treasury; Defense; Interior; Agriculture; Commerce; Labor; Health and Human Services; Education; Housing and Urban Development; Transportation; Energy; and Veterans' Affairs.
The Congress of the United States, the legislative branch, is bicameral and consists of the Senate and the House of Representatives. The judicial branch is formed by the federal courts and headed by the U.S. Supreme Court. The members of the Congress are elected by universal suffrage (see election) as are the members of the electoral college, which formally chooses the President and the Vice President.
