The United States of America (USA), commonly called the United States or America, is a country primarily located in North America. It is a federal republic made up of 50 states and a federal capital district, Washington, D.C., with additional territories in the Caribbean and the Pacific. Its land area is among the largest in the world, and its population is also among the world’s largest.
The country’s origins lie in the colonial era, when English settlements spread along the Atlantic coast. Tensions with Great Britain over taxation and political rights led to the American Revolution, and the United States Declaration of Independence was adopted in 1776. After victory in the American Revolutionary War, the new nation expanded westward, often through purchase, settlement, and conflict. In the 19th century, disputes over slavery culminated in the American Civil War, after which slavery was abolished nationally and the Union preserved.
The United States has a federal constitutional system with separation of powers among the legislative, executive, and judicial branches. Congress of the United States is bicameral, consisting of the United States House of Representatives and the United States Senate. The federal system gives substantial autonomy to the states.
Today, the United States is a developed country with the world’s largest economy by nominal GDP and a major global role in politics, culture, finance, and military affairs. Its society has been shaped by centuries of immigration, and its culture has had wide international influence.