United States of America
Flag of the United States Great Seal of the United States
Flag Great Seal
Motto: In God We Trust  
E Pluribus Unum  
Anthem: "The Star-Spangled Banner"
Location of the United States
Capital Washington, D.C.
38°53′N 77°01′W / 38.883°N 77.017°W / 38.883; -77.017
Largest city New York City
Official languages None at federal level1
National language English 2
Demonym American
Government Federal constitutional republic
 -  President Barack Obama " title="Democratic Party ">D)
 -  Vice President Joe Biden " title="Democratic Party ">D)
 -  Speaker of the House Nancy Pelosi " title="Democratic Party ">D)
 -  Chief Justice John Roberts
Independence from the Kingdom of Great Britain
 -  Declared July 4, 1776 
 -  Recognized September 3, 1783 
 -  Current constitution June 21, 1788 
Area
 -  Total 9,826,630 km2 
3,794,066 sq mi 
 -  Water  6.76
Population
 -  2009 estimate 306,161,000 
 -  2000 census 281,421,906 
 -  Density 31/km2 
80/sq mi
GDP  2008 estimate
 -  Total $14.334 trillion " title="List of countries by GDP ">1st)
 -  Per capita $47,025 _per_capita" title="List of countries by GDP per capita">6th)
GDP 2008 estimate
 -  Total $14.334 trillion " title="List of countries by GDP ">1st)
 -  Per capita $47,025 _per_capita" title="List of countries by GDP per capita">17th)
Gini  46.3 
HDI  0.950  
Currency United States dollar
Time zone
 -  Summer   
Drives on the Right
Internet TLD .us .gov .mil .edu
Calling code 1
1 English is the official language of at least 28 states—some sources give a higher figure, based on differing definitions of "official". English and Hawaiian are both official languages in the state of Hawaii.
2 English is the de facto language of American government and the sole language spoken at home by 82% of Americans age five and older. Spanish is the second most commonly spoken language.
3 Whether the United States or the People's Republic of China is larger is disputed. The figure given is from the U.S. Central Intelligence Agency's World Factbook. Other sources give smaller figures. All authoritative calculations of the country's size include only the fifty states and the District of Columbia, not the territories.
4 The population estimate includes people whose usual residence is in the fifty states and the District of Columbia, including noncitizens. It does not include either those living in the territories, amounting to more than 4 million U.S. citizens , or U.S. citizens living outside the United States.

The United States of America is a federal constitutional republic comprising fifty states and a federal district. The country is situated mostly in central North America, where its forty-eight contiguous states and Washington, D.C., the capital district, lie between the Pacific and Atlantic Oceans, bordered by Canada to the north and Mexico to the south. The state of Alaska is in the northwest of the continent, with Canada to its east and Russia to the west across the Bering Strait. The state of Hawaii is an archipelago in the mid-Pacific. The country also possesses several territories, or insular areas, in the Caribbean and Pacific.

At 3.79 million square miles and with about 306 million people, the United States is the third or fourth largest country by total area, and third largest by land area and by population. The United States is one of the world's most ethnically diverse and multicultural nations, the product of large-scale immigration from many countries. The U.S. economy is the largest national economy in the world, with an estimated 2008 gross domestic product of US $14.3 trillion .

The nation was founded by thirteen colonies of Great Britain located along the Atlantic seaboard. On July 4, 1776, they issued the Declaration of Independence, which proclaimed their independence from Great Britain and their formation of a cooperative union. The rebellious states defeated Great Britain in the American Revolutionary War, the first successful colonial war of independence. The Philadelphia Convention adopted the current United States Constitution on September 17, 1787; its ratification the following year made the states part of a single republic with a strong central government. The Bill of Rights, comprising ten constitutional amendments guaranteeing many fundamental civil rights and freedoms, was ratified in 1791.

In the 19th century, the United States acquired land from France, Spain, the United Kingdom, Mexico, and Russia, and annexed the Republic of Texas and the Republic of Hawaii. Disputes between the agrarian South and industrial North over states' rights and the expansion of the institution of slavery provoked the American Civil War of the 1860s. The North's victory prevented a permanent split of the country and led to the end of legal slavery in the United States. By the 1870s, the national economy was the world's largest. The Spanish–American War and World War I confirmed the country's status as a military power. In 1945, the United States emerged from World War II as the first country with nuclear weapons, a permanent member of the United Nations Security Council, and a founding member of NATO. The end of the Cold War and the dissolution of the Soviet Union left the United States as the sole superpower. The country accounts for approximately 50% of global military spending and is a leading economic, political, and cultural force in the world.

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