a federal republic mainly in North America consisting of 50 states and the District of Columbia: colonized principally by the English and French in the 17th century, the indigenous inhabitants being gradually defeated and displaced; 13 colonies under British rule made the Declaration of Independence in 1776 and became the United States after the War of American Independence. The northern states defeated the South in the Civil War (1861–65). It is the world's most productive industrial nation and also exports agricultural products. It consists generally of the Rocky Mountains in the west, the Great Plains in the centre, the Appalachians in the east, deserts in the southwest, and coastal lowlands and swamps in the southeast. Language: predominantly English; Spanish is also widely spoken. Religion: Christian majority. Currency: dollar. Capital: Washington, DC. Pop: 324 459 463 (2017 est). Area: 9 518 323 sq km (3 675 031 sq miles)