Arlington County, Virginia area. The county is situated in Northern Virginia on the southwestern bank of the Potomac River directly across from Washington, D.C., of which it was once a part. With a land area of , Arlington is the geographically smallest self-governing county in the U.S., and by reason of state law regarding population density, has no incorporated towns within its borders. Due to the county's proximity to downtown Washington, D.C., Arlington is home to many important installations for the capital region and U.S. government, including the Pentagon, Reagan National Airport, and Arlington National Cemetery. Many schools and universities have campuses in
U.S. Route 50 in the District of Columbia U.S. Route 50 in the District of Columbia U.S. Route 50 (US 50) is a major east–west route of the U.S. Highway system, stretching just over from Ocean City, Maryland, on the Atlantic Ocean, to West Sacramento, California, nearly to the Pacific Ocean. In the District of Columbia, US 50 passes between Arlington County, Virginia, and Prince George's County, Maryland, predominantly along surface streets, including a part of Constitution Avenue along the National Mall. US 50 enters the District of Columbia from Arlington, Virginia, merging with I-66 on the Theodore Roosevelt Bridge over the Potomac River. US 50 traffic exits