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.[j] Outside the union of states, it asserts sovereignty over five major unincorporated island territories and various uninhabited islands.[k] The country has the world’s third-largest land area,[d] second-largest exclusive economic zone, and third-
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,
The U.S. national government is a presidential constitutional republic and liberal democracy with three separate branches: legislative, executive, and judicial. It has a bicameral national legislature composed of the House of Representatives, a lower house based on population; and the Senate, an upper house based on equal representation for each state. Substantial autonomy is given to states and several territories, with a political culture that emphasizes liberty, equality under the law, individualism, and