Washington, D.C., formally known as the District of Columbia, is the capital of the United States. The Residence Act, signed on July 16, 1790, established a federal district along the Potomac River on the East Coast. As outlined in the U.S. Constitution, this district operates under the exclusive jurisdiction of Congress, meaning it is not part of any state.

The land for the District was donated by the states of Maryland and Virginia, incorporating existing settlements like Georgetown and Alexandria. Founded in 1791 and named after George Washington, the City of Washington was intended to be the new national capital. In 1846, Congress returned the portion of land ceded by Virginia, and in 1871, a unified municipal government was created for the remaining District.

As of 2014, Washington, D.C. had an estimated population of 658,893, ranking it as the 22nd most populous city in the country. The city’s population can exceed one million during the workweek due to commuters from the surrounding Maryland and Virginia suburbs. The Washington metropolitan area, which includes the District, has a total population of 5.8 million, making it the seventh-largest metropolitan statistical area in the U.S.

The District is home to the three branches of the U.S. federal government—Congress, the President, and the Supreme Court. It boasts numerous national monuments and museums, primarily located around the National Mall. Additionally, Washington is home to 176 foreign embassies, as well as the headquarters of various international organizations, trade unions, non-profits, lobbying groups, and professional associations.