The United States of America (USA or U.S.A.), commonly known as the United States (US or U.S.) or America, is a country primarily located in North America. It is a federation of 50 states, a federal capital district (Washington, D.C.), and 326 Indian reservations. Outside the union of states, it asserts sovereignty over five major unincorporated island territories and various uninhabited islands. The country has the world's third-largest land area, second-largest exclusive economic zone, and third-largest population, exceeding 334 million.

Paleo-Indians migrated across the Bering land bridge more than 12,000 years ago. British colonization led to the first settlement of the Thirteen Colonies in Virginia in 1607. Clashes with the British Crown over taxation and political representation sparked the American Revolution, with the Second Continental Congress formally declaring independence on July 4, 1776. Following its victory in the Revolutionary War (1775–1783), the country continued to expand across North America. As more states were admitted, sectional division over slavery led to the secession