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
Arlington County, Virginia county having the same name, a movement started to rename Alexandria County. In 1920, the name Arlington County was adopted, after Arlington House, the home of the American Civil War Confederate general Robert E. Lee, which stands on the grounds of what is now Arlington National Cemetery. The Town of Potomac was incorporated as a town in Alexandria County in 1908. The town was annexed by the independent city of Alexandria in 1930. In 1896, an electric trolley line was built from Washington through Ballston, which led to growth in the county (see Northern Virginia trolleys). In 1920, the Virginia