| About USA |
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 The United States of America (USA), commonly referred to as the United States (U.S.) or America, is a federal republic[19][20] composed of 50 states, a federal district, five major territories and various possessions.[fn 1][fn 2] The 48 contiguous states and Washington, D.C., are in central North America between Canada and Mexico. The state of Alaska is in the northwestern part of North America and the state of Hawaii is an archipelago in the mid-Pacific. The territories are scattered about the Pacific Ocean and the Caribbean Sea. At 3.8 million square miles (9.842 million km2)[18] and with over 320 million people, the country is the world's third or fourth-largest by total area[fn 3] and the third most populous. It is one of the world's most ethnically diverse and multicultural nations, the product of large-scale immigration from many countries.[26] The geography and climate of the United States are also extremely diverse, and the country is home to a wide variety of wildlife.[27]
Paleo-Indians migrated from Eurasia to what is now the U.S. mainland at least 15,000 years ago,[28] with European colonization beginning in the 16th century. The United States emerged from 13 British colonies along the East Coast. Disputes between Great Britain and the colonies led to the American Revolution. On July 4, 1776, as the colonies were fighting Great Britain in the American Revolutionary War, delegates from the 13 colonies unanimously adopted the Declaration of Independence. The war ended in 1783 with recognition of the independence of the United States by the Kingdom of Great Britain, and was the first successful war of independence against a European colonial empire.[29] The country's constitution was adopted on September 17, 1787, and ratified by the states in 1788. The first ten amendments, collectively named the Bill of Rights, were ratified in 1791 and designed to guarantee many fundamental civil liberties. |
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Etymology
See also: Names for United States citizens and Names of the United States
In 1507, the German cartographer Martin Waldseemüller produced a world map on which he named the lands of the Western Hemisphere "America" after the Italian explorer and cartographer Amerigo Vespucci (Latin: Americus Vespucius).[41] The first documentary evidence of the phrase "United States of America" is from a letter dated January 2, 1776, written by Stephen Moylan, Esq., George Washington's aide-de-camp and Muster-Master General of the Continental Army. Addressed to Lt. Col. Joseph Reed, Moylan expressed his wish to carry the "full and ample powers of the United States of America" to Spain to assist in the revolutionary war effort.[42]
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.[43][44] 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.[45][46] In the final Fourth of July version of the Declaration, the title was changed to read, "The unanimous Declaration of the thirteen united States of America".[47] In 1777 the Articles of Confederation announced, "The Stile of this Confederacy shall be 'The United States of America'".[48] The preamble of the Constitution states "...establish this Constitution for the United States of America." |
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History
 Main articles: History of the United States, Timeline of United States history, Economic history of the United States and Labor history of the United States
Native Americans meeting with Europeans, 1764
Indigenous and European contact
Further information: Pre-Columbian era and Colonial history of the United States
The first inhabitants of North America migrated from Siberia by way of the Bering land bridge and arrived at least 15,000 years ago, though increasing evidence suggests an even earlier arrival.[28] Some, such as the pre-Columbian Mississippian culture, developed advanced agriculture, grand architecture, and state-level societies. After the Spanish conquistadors made the first contacts, the native population declined for various reasons, primarily diseases such as smallpox and measles. Violence was not a significant factor in the overall decline, though it impacted specific tribes and colonial settlements.[54][55][56][57][58][59] In the Hawaiian Islands the earliest indigenous inhabitants arrived around 1 AD from Polynesia. Captain James Cook arrived in the Hawaiian Islands in 1778[60] with American contact made in 1790 with the first ship to dock arriving in Oahu.[61]
In the early days of colonization many European settlers were subject to food shortages, disease, and attacks from Native Americans. Native Americans were also often at war with neighboring tribes and allied with Europeans in their colonial wars.[62] At the same time, however, many natives and settlers came to depend on each other. Settlers traded for food and animal pelts, natives for guns, ammunition and other European wares.[63] Natives taught many settlers where, when and how to cultivate corn, beans and squash. European missionaries and others felt it was important to "civilize" the Indians and urged them to adopt European agricultural techniques and lifestyles. |
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Geography, climate, and environment
Main articles:
Geography of the United States, Climate of the United States and Environment of the United States
A composite satellite image of the contiguous United States and surrounding areas.
The northeastern U.S. coast seen from the International Space Station. The New York City area is visible in the lower right quadrant, while Philadelphia and Washington, D.C. are near the center.[169]
The land area of the contiguous United States is 2,959,064 square miles (7.7 Mm2). Alaska, separated from the contiguous United States by Canada, is the largest state at 663,268 square miles (1.7 Mm2). 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 US Virgin Islands together cover 9,185 square miles (23,789 km2)[170]
The United States is the world's third or fourth 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 (9.5 Mm2)[171] to 3,717,813 square miles (9.6 Mm2)[172] to 3,794,101 square miles (9.8 Mm2)[5] to 3,805,927 square miles (9.9 Mm2).[18] Measured by only land area, the United States is third in size behind Russia and China, just ahead of Canada.[173]
The coastal plain of the Atlantic seaboard gives way further inland to deciduous forests and the rolling hills of the Piedmont.[174] The Appalachian Mountains divide the eastern seaboard from the Great Lakes and the grasslands of the Midwest.[175] 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.
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