District of Columbia - geography.

District of Columbia - geography. District of Columbia, federal district of the United States, coextensive with the city of Washington, D.C., the national capital. It is situated on the Potomac and Anacostia rivers and has an area of 176 sq km (68 sq mi). Government departments and agencies are the major source of employment in the District. Other important industries are tourism, including the convention trade; scientific research and development; and the manufacture of technical equipment. The District is well known for its cultural institutions, historic landmarks, and parks. Bills passed by the U.S. Congress in 1790 and 1791 created the District on a tract of land ceded by Maryland and Virginia. The area contained the communities of Alexandria and Washington. The cornerstone of the U.S. Capitol was laid in 1793, and in 1800 the Congress of the United States moved here from its temporary headquarters in Philadelphia. In 1846, Congress agreed to return Alexandria and the remainder of the District on the western bank of the Potomac to the state of Virginia. Georgetown held the status of a separate town within the District from 1878 to 1895, when it was merged with Washington. Population (1980) 638,432; (1990) 606,900; (2007 estimate) 588,292. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.