Department of Defense police for the Department of Defense and its component branches of the US Armed Forces. There is a DoD police agency based at the Pentagon named the United States Pentagon Police, which is part of the Pentagon Force Protection Agency. Formerly the Defense Protective Service (DPS), the Pentagon Police have exclusive jurisdiction within the Pentagon Reservation and have concurrent jurisdiction with other police agencies (state, county, and local) in an area of approximately around the complex. Through a memorandum of understanding (MOU) with Arlington County, U.S. Pentagon Police Officers also possess authority, to enforce laws while on duty in Arlington County,
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