The United States of America (USA), commonly known as the United States (U.S.) or America, is a Federal Republic composed of 50 States, a Federal District, five major Self-Governing Territories, and various possesions. Forty-eight States and the Federal District are contiguous and located in North America between Canada and Mexico. The State of Alaska is in the northwest corner of North America, bordered by Canada to the east and across the Bering Strait from Russia to the west. The State of Hawaii is an archipelago in the mid-Pacific Ocean. The U.S. territories are scattered about the Pacific Ocean and the Caribbean Sea, stretching across nine official time zones. The extremely diverse geography, climate and wildlife of the United States make it one of the world's 17 mega-diverse countries.
At 3,8 million square miles (9,8 million km2) and with over 324 million people, the United States is the world's third largest country by total area, and the third most populous. The Capital City is Washington, D.C., and the largest City is New York City; twelve other major metropolitan areas, each with at least 4,5 million inhabitants are Los Angeles, Chicago, Dallas, Houston, Washington, D.C., Philadelphia, Miami, Atlanta, Boston, San Francisco, Phoenix, and Riverside - San Bernardino.
The United States is a highly developed country, with the world's largest economy by nominal GDP and second largest economy by PPP, accounting for approximately a quarter of global GDP. The U.S. economy is the fastest-growing in the Americas and is largely post-industrial, characterized by the dominance of services and knowledge based activities, although the manufacturing sector remains the second largest in the world.
Though its population is only 4,3% of the world total, Americans hold 33,2% of the total wealth in the world, the largest share of global wealth concentrated in a single country. The United States ranks among the highest nations in several measures of socioeconomic performance, including average wage, human development, per-capita GDP, and productivity per person. The U.S. is the foremost military power in the world, making up a third of global military spending. It is also a global leader in science and technology.
The land area of the contiguous United States is 2.959.064 square miles (7.663.940,6 km2). Alaska, separated from the contiguous United States by Canada, is the largest state at 663.268 square miles (1.717.856,2 km2). Hawaii, occupying an archipelago in the central Pacific, southwest of North America, is 10.931 square miles (28.311 km2) in area. The populated territories of Puerto Rico, American Samoa, Guam, Northern Mariana Islands, and U.S. Virgin Islands together cover 9.185 square miles (23.789 km2). Measured by only land area, the United States is third in size behind Russia, and China, just ahead of Canada.
The United States is the world's third largest nation by total area (land and water), ranking behind Russia and Canada and just above or below China. The ranking varies depending on how two territories disputed by China and India are counted and how the total size of the United States is measured : calculations range from 3.676.486 square miles (9.522.055,0 km2) to 3.717.813 square miles (9.629.091,5 km2) to 3.796.742 square miles (9.833.516,6 km2).
The coastal plain of the Atlantic seaboard gives way further inland to deciduous forests and the rolling hills of the Piedmont. The Appalachian Mountains divide the Eastern seaboard from the Great Lakes and the grasslands of the Midwest. The Mississippi - Missouri River, the world's fourth longest river system, runs mainly North - South through the heart of the country. The flat, fertile prairie of the Great Plains stretches to the West, interrupted by a highland region in the Southeast.
The Rocky Mountains, at the western edge of the Great Plains, extend north to south across the country, reaching altitudes higher than 14,000 feet (4,300 m) in Colorado. Farther west are the rocky Great Basin and deserts such as the Chihuahua and Mojave. The Sierra Nevada and Cascade mountain ranges run close to the Pacific coast, both ranges reaching altitudes higher than 14.000 feet (4.300 m). The lowest and highest points in the contiguous United States are in the state of California, and only about 84 miles (135 km) apart. At an elevation of 20.310 feet (6.190.5 m), Alaska's Denali (Mount McKinley) is the highest peak in the country and North America. Active volcanoes are common throughout Alaska's Alexander and Aleutian Islands, and Hawaii consists of volcanic islands. The supervolcano underlying Yellowstone National Park in the Rockies is the continent's largest volcanic feature. The United States has the most ecoregions out of any country in the world.
The United States, with its large size and geographic variety, includes most climate types. To the east of the 100th meridian, the climate ranges from humid continental in the north to humid subtropical in the south. The Great Plains west of the 100th meridian are semi - arid. Much of the Western mountains have an alpine climate. The climate is arid in the Great Basin, desert in the Southwest, Mediterranean in coastal California, and oceanic in coastal Oregon and Washington and southern Alaska. Most of Alaska is subarctic or polar. Hawaii and the southern tip of Florida are tropical, as are the populated territories in the Caribbean and the Pacific. Extreme weather is not uncommon, the states bordering the Gulf of Mexico are prone to hurricanes, and most of the world's tornadoes occur within the country, mainly in Tornado Alley areas in the Midwest and South.
English (American English) is the de facto national language. Although there is no official language at the federal level, some laws such as U.S. naturalization requirements standardize English. In 2010, about 230 million, or 80% of the population aged five years and older, spoke only English at home. Spanish, spoken by 12% of the population at home, is the second most common language and the most widely taught second language. Some Americans advocate making English the country's official language, as it is in 32 states.
Both Hawaiian and English are official languages in Hawaii, by state law. Alaska recognizes twenty Native languages as well as English. While neither has an official language, New Mexico has laws providing for the use of both English and Spanish, as Louisiana does for English and French. Other states, such as California, mandate the publication of Spanish versions of certain government documents including court forms.
Several insular territories grant official recognition to their native languages, along with English : Samoan and Chamorro are recognized by American Samoa and Guam, respectively; Carolinian and Chamorro are recognized by the Northern Mariana Islands; Spanish is an official language of Puerto Rico and is more widely spoken than English there.
The most widely taught foreign languages in the United States, in terms of enrollment numbers from Kindergarten through University Undergraduate Studies, are: Spanish (around 7,2 million students), French (1,5 million), and German (500,000). Other commonly taught languages (with 100,000 to 250,000 learners) include Latin, Japanese, ASL, Italian, and Chinese. 18% of all Americans claim to speak at least one language in addition to English.
The United States is the world's oldest surviving Federation. It is a representative democracy, "in which majority rule is tempered by minority rights protected by law". The government is regulated by a system of checks and balances defined by the U.S. Constitution, which serves as the country's supreme legal document. For 2016, the U.S. ranked 21st on the Democracy Index (tied with Italy) and 18th on the Corruption Perceptions Index.
In the American Federalist system, citizens are usually subject to three levels of government : Federal, State, and Local. The Local Governmentâ€™s duties are commonly split between County and Municipal Governments. In almost all cases, Executive and Legislative Officials are elected by a plurality vote of Citizens by District. There is no proportional representation at the federal level, and it is rare at lower levels.
The United States is a Federal Republic of 50 states, a Federal District, five Territories and eleven uninhabited island possessions. The States and Territories are the principal administrative districts in the country. These are divided into subdivisions of counties and independent cities. The District of Columbia is a federal district that contains the capital of the United States, Washington DC. The states and the District of Columbia choose the President of the United States. Each state has presidential electors equal to the number of their Representatives and Senators in Congress; the District of Columbia has three.
Congressional Districts are reapportioned among the states following each decennial Census of Population. Each state then draws single member districts to conform to the census apportionment. The total number of Representatives is 435, and delegate Members of Congress represent the District of Columbia and the five major U.S. territories.
The United States also observes tribal sovereignty of the American Indian nations to a limited degree, as it does with the states' sovereignty. American Indians are U.S. citizens and tribal lands are subject to the jurisdiction of the U.S. Congress and the federal courts. Like the states they have a great deal of autonomy, but also like the states, tribes are not allowed to make war, engage in their own foreign relations, or print and issue currency.
American public education is operated by state and local governments, regulated by the United States Department of Education through restrictions on federal grants. In most states, children are required to attend school from the age of six or seven (generally, kindergarten or first grade) until they turn 18 (generally bringing them through twelfth grade, the end of high school); some states allow students to leave school at 16 or 17.
About 12% of children are enrolled in parochial or nonsectarian private schools. Just over 2% of children are homeschooled. The U.S. spends more on education per-student than any nation in the world, spending more than $11.000 per-elementary student in 2010 and more than $12.000 per-high school student. Some 80% of U.S. college students attend public universities.
The United States has many competitive private and public institutions of higher education. The majority of the world's top universities listed by different ranking organizations are in the U.S. There are also local community colleges with generally more open admission policies, shorter academic programs, and lower tuition. Of Americans 25 and older, 84.6% graduated from high school, 52.6% attended some college, 27.2% earned a bachelor's degree, and 9.6% earned graduate degrees. The basic literacy rate is approximately 99%. The United Nations assigns the United States an Education Index of 0.97, tying it for 12th in the world.
As for public expenditures on higher education, the U.S. trails some other OECD nations but spends more per-student than the OECD average, and more than all nations in combined public and private spending. As of 2012, student loan debt exceeded one trillion dollars, more than Americans owe on credit cards.