United States

The United States of America (USA), commonly known as the United States (U.S.) or America, is a constitutional federal republic composed of 50 states, a federal district, five major self-governing territories, and various possessions. Forty-eight of the fifty 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. Nine time zones are covered. The geography, climate and wildlife of the country are extremely diverse.

Approaching Omaha.jpg U.S. troops approaching Omaha Beach in 1944

At 3.8 million square miles (9.8 million km2) and with over 324 million people, the United States is the world's third- or fourth-largest country by total area, third-largest by land area, and the third-most populous. It is one of the world's most ethnically diverse and multicultural nations, and is home to the world's largest immigrant population. The capital is Washington, D.C., and the largest city is New York City; nine other major metropolitan areas—each with at least 4.5 million inhabitants and the largest having more than 13 million people—are Los Angeles, Chicago, Dallas, Houston, Philadelphia, Miami, Atlanta, Boston, and San Francisco.

Bald Eagle Portrait.jpg The bald eagle has been the national bird of the United States since 1782.

Paleo-Indians migrated from Asia to the North American mainland at least 15,000 years ago. European colonization began in the 16th century. The United States emerged from 13 British colonies along the East Coast. Numerous disputes between Great Britain and the colonies following the Seven Years' War led to the American Revolution, which began in 1775. On July 4, 1776, during the course of the American Revolutionary War, the colonies unanimously adopted the Declaration of Independence. The war ended in 1783 with recognition of the independence of the United States by Great Britain, representing the first successful war of independence against a European power. The current constitution was adopted in 1788, after the Articles of Confederation, adopted in 1781, were felt to have provided inadequate federal powers. The first ten amendments, collectively named the Bill of Rights, were ratified in 1791 and designed to guarantee many fundamental civil liberties.

Capitol Building Full View.jpg The United States Capitol, where Congress meets: the Senate, left; the House, right The White House, home and principal workplace of the U.S. President Supreme Court Building, where the nation's highest court sits

The United States embarked on a vigorous expansion across North America throughout the 19th century, displacing Native American tribes, acquiring new territories, and gradually admitting new states until it spanned the continent by 1848. During the second half of the 19th century, the American Civil War led to the end of legal slavery in the country. By the end of that century, the United States extended into the Pacific Ocean, and its economy, driven in large part by the Industrial Revolution, began to soar. 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, the first country to develop nuclear weapons, the only country to use them in warfare, and a permanent member of the United Nations Security Council. The end of the Cold War and the dissolution of the Soviet Union in 1991 left the United States as the world's sole superpower. The U.S. is a founding member of the United Nations, World Bank, International Monetary Fund, Organization of American States (OAS), and other international organizations.

Castillo de San Marcos.jpg Castillo de San Marcos in St. Augustine, Florida, the oldest continuously occupied European-established settlement in the United States

The United States is a highly developed country, with the world's largest economy by nominal GDP and second-largest economy by PPP. It ranks highly in several measures of socioeconomic performance, including average wage, human development, per capita GDP, and productivity per person. While the U.S. economy is considered post-industrial, characterized by the dominance of services and knowledge economy, the manufacturing sector remains the second-largest in the world. Though its population is only 4.3% of the world total, the United States accounts for nearly a quarter of world GDP and over a third of global military spending, making it the world's foremost economic and military power. The United States is a prominent political and cultural force internationally, and a leader in scientific research and technological innovations.

Census-2000-Data-Top-US-Ancestries-by-County.svg Largest ancestry groups by county (2000), led by German Americans
ChicagoFromCellularField.jpg Chicago
Chromesun kincaid site 01.jpg An artistic recreation of The Kincaid Site from the prehistoric Mississippian culture as it may have looked at its peak 1050–1400 AD
Columbus Taking Possession.jpg Italian explorer Christoper Columbus arrives in America and takes possession of Guanahani
Declaration independence.jpg The Declaration of Independence: the Committee of Five presenting their draft to the Second Continental Congress in 1776
Donald Trump official portrait.jpg Donald Trump, the President of the United States since January 20, 2017
Downtown Dallas from the Trinity River.jpg Dallas
Ellis island 1902.jpg Ellis Island in New York City was a major gateway for European immigration.
Flag of the United States.svg Flag of the United States
Great Seal of the United States (obverse).svg Great Seal of the United States
LA Skyline Mountains2.jpg Los Angeles
Liberty-statue-from-below.jpg The Statue of Liberty in New York City is a symbol of both the U.S. and the ideals of freedom, democracy, and opportunity.
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ReaganBerlinWall.jpg U.S. President Ronald Reagan at his "Tear down this wall!" speech in Berlin, Germany on June 12, 1987. The Iron Curtain of Europe manifested the division of the world's superpowers during the Cold War.
The Mayflower Compact 1620 cph.3g07155.jpg The signing of the Mayflower Compact, 1620
Thure de Thulstrup - L. Prang and Co. - Battle of Gettysburg - Restoration by Adam Cuerden (cropped).jpg The Battle of Gettysburg, Pennsylvania during the Civil War by Thure de Thulstrup
Top of Rock Cropped.jpg New York City
U.S. Territorial Acquisitions.png U.S. territorial acquisitions–portions of each territory were granted statehood since the 18th century.
US50states koppen.svg Köppen climate classifications
USA-satellite.jpg A composite satellite image of the contiguous United States and surrounding areas
USA orthographic.svg The contiguous United States plus Alaska and Hawaii
USSupremeCourtWestFacade.JPG
US insular areas.svg The United States and its territories
Us population 2005 lrg.jpg U.S. population density in 2005
WTC smoking on 9-11.jpeg The World Trade Center in Lower Manhattan during the September 11 attacks in 2001 One World Trade Center, newly-built in its place
WhiteHouseSouthFacade.JPG

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