Arlington

Arlington, county, north-eastern Virginia, on the Potomac River, opposite Washington, DC. It is a residential suburb of Washington and contains many United States government offices, notably the Pentagon, headquarters of the Department of Defense. Washington National Airport, Arlington National Cemetery, and Fort Myer Military Reservation are here. Educational institutions include Marymount University (1950).

Captain John Smith, the English colonist, explored the region of modern Arlington County in 1608. It became part of the huge Fairfax land grant and in about 1700 was divided into 15 plantations. The area was ceded to the US government in 1791 as part of the new national capital; because Washington failed to expand across the Potomac, the land was returned to Virginia in 1846. During the American Civil War it was occupied by Union troops. In 1920 the county was separated from the city of Alexandria and was named after Arlington House, the home here of the Confederate general Robert E. Lee. Population (1980) 152,599; (1990) 170,936.