High Quality Content by WIKIPEDIA articles! State Route 7 (SR 7) is a major primary state highway and busy commuter route in Northern Virginia, United States. It travels southeast from downtown Winchester to SR 400 (Washington Street) in downtown Alexandria. Its route largely parallels those of the Washington & Old Dominion Trail (W&OD Trail) and the Potomac River. West of I-395, SR 7 is part of the National Highway System.