The line followed the winding course of Four Mile Run upstream from Alexandria through Arlington to Falls Church. At that point, the railroad was above the Fall Line and was able to follow a more direct northwesterly course in Virginia through Dunn Loring, Vienna, Sunset Hills (now in Reston), Herndon, Sterling, Ashburn, Leesburg, Paeonian Springs, Hamilton, Purcellville and Round Hill to its terminus at Bluemont, turning sharply to the west only after passing through Clarke's Gap in Catoctin Mountain west of Leesburg. A branch connected the line to Rosslyn. The Washington & Old Dominion Railroad Trail (W&OD Trail), the Bluemont Junction Trail, the Mount Jefferson Park and Greenway Trail, several other trails, Interstate 66 (I-66), and Old Dominion Drive (Virginia State Route 309) have replaced much of the railroad's route.