United States

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"America", "US", and "USA" redirect here. For the landmass comprising North, Central, South America, and the Caribbean, see Americas. For other uses, see America (disambiguation), US (disambiguation), USA (disambiguation), and United States (disambiguation).

United States of America

Motto: 
Projection of North America with the United States in green
The United States and its territories
The United States, including its territories
Capital
Largest city
Official languagesNone at federal level[a]
National languageEnglish[b]
Ethnic groups
(2018)[6]
By race:
Ethnicity:
Religion
(2017)[7]
Demonym(s)American[c][8]
GovernmentFederal presidential constitutional republic
• President
Donald Trump (R)
Mike Pence (R)
Nancy Pelosi (D)
John Roberts
LegislatureCongress
Senate
House of Representatives
Independence 
July 4, 1776
March 1, 1781
September 3, 1783
June 21, 1788
Area
• Total area
3,796,742 sq mi (9,833,520 km2)[d][9] (3rd/4th)
• Water (%)
6.97
• Total land area
3,531,905 sq mi (9,147,590 km2)
Population
• 2018 estimate
Increase327,167,434[e][10] (3rd)
• 2010 census
308,745,538[e][11] (3rd)
• Density
87/sq mi (33.6/km2) (146th)
GDP (PPP)2018 estimate
• Total
$20.580 trillion[12] (2nd)
• Per capita
$62,869[12] (11th)
GDP (nominal)2018 estimate
• Total
$20.580 trillion[12] (1st)
• Per capita
$62,869[12] (7th)
Gini (2016)Negative increase 41.5[13]
medium · 56th
HDI (2018)Decrease 0.920[14]
very high · 15th
CurrencyUnited States dollar ($) (USD)
Time zoneUTC−4 to −12, +10, +11
• Summer (DST)
UTC−4 to −10[f]
Date format
  • mm/dd/yyyy
  • yyyy-mm-dd[15]
Mains electricity120 V–60 Hz
Driving sideright[g]
Calling code+1
ISO 3166 codeUS
Internet TLD

The United States of America (USA), commonly known as the United States (U.S. or US) or simply America, is a country comprising 50 states, a federal district, five major self-governing territories, and various possessions.[i] At 3.8 million square miles (9.8 million km2), it is the world's third or fourth largest country by total area[d] and is slightly smaller than the entire continent of Europe. Most of the country is located in central North America between Canada and Mexico. With an estimated population of over 327 million people, the U.S. is the third most populous country. The capital is Washington, D.C., and the most populous city is New York City.

Paleo-Indians migrated from Siberia to the North American mainland at least 12,000 years ago.[21] European colonization began in the 16th century. The United States emerged from the thirteen British colonies established along the East Coast. Numerous disputes between Great Britain and the colonies led to the American Revolutionary War lasting between 1775 and 1783, leading to independence.[22] The United States embarked on a vigorous expansion across North America throughout the 19th century, gradually acquiring new territories,[23] displacing Native Americans, and admitting new states until spanning the continent by 1848.[23]During the second half of the 19th century, the American Civil War led to the abolition of slavery in the United States.[24][25] The Spanish–American War and World War I confirmed the country's status as a global military power.

The United States emerged from World War II as a global superpower. It was the first country to develop nuclear weapons, and the only one to use them in warfare. During the Cold War, the United States and the Soviet Union competed in the Space Race, culminating with the 1969 Apollo 11 mission, the spaceflight that first landed humans on the Moon. The end of the Cold War and collapse of the Soviet Union in 1991 left the United States as the world's sole superpower.[26]

The United States is a federal republic and a representative democracy. It is a founding member of the United Nations, World Bank, International Monetary Fund, Organization of American States (OAS), NATO, and other international organizations. It is a permanent member of the United Nations Security Council.

A highly developed country, the United States is the world's largest economy by nominal GDP, the second-largest by purchasing power parity, and accounts for approximately a quarter of global GDP.[27] The United States is the world's largest importer and the second-largest exporter of goods, by value.[28][29] Although its population is 4% of the world total,[30] it holds 31% of the total wealth in the world, the largest share of global wealth concentrated in a single country.[31] Despite income and wealth disparities, the United States continues to rank very high in measures of socioeconomic performance, including average wage, median income, median wealth, human development, per capita GDP, and worker productivity.[32][33] It is the foremost military power in the world, making up a third of global military spending,[34] and is a leading political, cultural, and scientific force internationally.[35]

Etymology

See also: Naming of the Americas, Names for United States citizens, and American (word)
Portrait of Amerigo Vespucci
The Americas are believed to be named for the Italian explorer Amerigo Vespucci.[36]

In 1507, the German cartographer Martin Waldseemüller produced a world map on which he named the lands of the Western Hemisphere America in honor of the Italian explorer and cartographer Amerigo Vespucci (Latin: Americus Vespucius).[37] The first documentary evidence of the phrase "United States of America" is from a letter dated January 2, 1776, written by Stephen Moylan, Esq., to George Washington's aide-de-camp and Muster-Master General of the Continental Army, Lt. Col. Joseph Reed. Moylan expressed his wish to go "with full and ample powers from the United States of America to Spain" to seek assistance in the revolutionary war effort.[38][39][40] The first known publication of the phrase "United States of America" was in an anonymous essay in The Virginia Gazette newspaper in Williamsburg, Virginia, on April 6, 1776.[41]

The second draft of the Articles of Confederation, prepared by John Dickinson and completed by June 17, 1776, at the latest, declared "The name of this Confederation shall be the 'United States of America'".[42] The final version of the Articles sent to the states for ratification in late 1777 contains the sentence "The Stile of this Confederacy shall be 'The United States of America'".[43] In June 1776, Thomas Jefferson wrote the phrase "UNITED STATES OF AMERICA" in all capitalized letters in the headline of his "original Rough draught" of the Declaration of Independence.[42] This draft of the document did not surface until June 21, 1776, and it is unclear whether it was written before or after Dickinson used the term in his June 17 draft of the Articles of Confederation.[42]

The short form "United States" is also standard. Other common forms are the "U.S.", the "USA", and "America". Colloquial names are the "U.S. of A." and, internationally, the "States". "Columbia", a name popular in poetry and songs of the late 18th century, derives its origin from Christopher Columbus; it appears in the name "District of Columbia." Many landmarks and institutions in the Western Hemisphere bear his name, including the country of Colombia.[44]

The phrase "United States" was originally plural, a description of a collection of independent states—e.g., "the United States are"—including in the Thirteenth Amendment to the United States Constitution, ratified in 1865.[45] The singular form—e.g., "the United States is"—became popular after the end of the American Civil War. The singular form is now standard; the plural form is retained in the idiom "these United States". The difference is more significant than usage; it is a difference between a collection of states and a unit.[46]

A citizen of the United States is an "American". "United States", "American" and "U.S." refer to the country adjectivally ("American values", "U.S. forces"). In English, the word "American" rarely refers to topics or subjects not directly connected with the United States.[47]