This gravel parking lot along the C&O Canal Towpath serves the National Park Service’s Paw Paw Tunnel Campground. The lots holds about thirty cars and can get very busy on the weekends. Free to park. Overnight parking allowed. The historic Paw Paw Tunnel is a 3,118-foot-long canal tunnel you can walk through on the Chesapeake and Ohio Canal in Allegany County, Maryland.