West Virginia was formed during the Civil War by anti-secession types who took as many counties as they thought they could get away with (many of the southern counties of WV were pro-Confederate and did not vote in the 1864 U.S. elections). The two easternmost counties were added later (apparently because the B&O Railroad could not collect damages if its lines were in a "rebel"state). The small bit of the Blue Ridge that is in WV is in one of those two counties.
Harper's Ferry is on the Potomac at the extreme eastern part of WV. The bridge over the Potomac River there is part of the Appalachian Trail (the only part of the Appalachian Trail I have walked).