The Great Allegheny Passage (GAP) is a rail trail in Maryland and Pennsylvania. It is the central trail of a network of long-distance hiker-biker trails covering hundreds of miles through the Allegheny region of the Appalachian Mountains, connecting Washington, D.C. to Pittsburgh, Pennsylvania and beyond. The multi-use trail, suitable for biking and walking, occupies abandoned corridors of the Baltimore and Ohio Railroad, Pittsburgh and Lake Erie Railroad, Union Railroad and the Western Maryland Railway. The Great Allegheny Passage extends 150 miles (240 km) from Cumberland, Maryland to Point State Park in downtown Pittsburgh, Pennsylvania, with a 52-mile (84 km) branch (Montour Trail) to the Pittsburgh International Airport. This GAP also connects with the Chesapeake and Ohio Canal towpath trail, which runs for an additional 185 miles (298 km) between Cumberland, Maryland and Washington, DC - creating a continuous non-motorized corridor, from Pittsburgh's Point State Park 339 miles (546 km)) to Washington, DC. The Great Allegheny Passage is a segment of the Potomac Heritage National Scenic Trail, one of eight nationally-designated scenic trails.