The Washington & Old Dominion Railroad Regional Park is a linear regional park in Northern Virginia. The park's primary feature is the Washington & Old Dominion Railroad Trail (abbreviated as W&OD Trail), an asphalt-surfaced paved rail trail that runs through densely populated urban and suburban communities as well as through rural areas. Most of the trail travels on top of the rail bed of the former Washington and Old Dominion Railroad, which closed in 1968.