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
Streets and highways of Arlington County, Virginia therefore, most roads are unnumbered. This status originated due to the existence of county highway departments in Arlington prior to the creation of the state transportation agency which is now the VDOT in 1927, and the assumption of local roads control by that agency in 1932. The control of the roads system is considered a powerful advantage for community urban planners, who can require developers to contribute to funding needed for road needs serving their projects. Although the streets of Arlington County are not laid out on a grid plan, its local streets follow the Arlington County, Virginia, street-naming system: