Joining the Shenandoah Valley to the Piedmont region of the state, it is the site of the mountain crossing of Interstate 64, U.S. Route 250, and the former Blue Ridge Railroad which later became part of the Chesapeake and Ohio Railway and is currently part of the CSX line. With an elevation of about , it is one of the lowest gaps between Manassas Gap and the James River. Rockfish Gap lies along a drainage divide between southeast-flowing streams that drain to the James River and northwest-flowing streams in the Shenandoah River system.