Great Allegheny Passage & C&O Tow Path Map Poster

The Great Allegheny Passage and the C&O Canal Towpath join end to end to make a 335 mi (539 km) car-free route from Pittsburgh to Washington, D.C. The GAP covers the first 150 mi (241 km), from Point State Park, where the Allegheny and Monongahela meet to form the Ohio, up the Youghiogheny through Ohiopyle, over the Salisbury Viaduct and through the Big Savage Tunnel to Cumberland, Maryland. There the towpath takes over for 184.5 mi (297 km), following the Potomac past the Paw Paw Tunnel, Harpers Ferry and Great Falls to Georgetown.

Most people ride it west to east in five to eight days, 45 to 60 mi (70 to 100 km) a day, and it is open to walkers too. The GAP is crushed limestone on old rail beds that never climb more than 2%. Its high point, the Eastern Continental Divide at 2,392 ft (729 m), comes about 1,700 ft (520 m) above the start. The towpath is dirt and packed gravel, with roots and puddles after rain.

The two halves come from two eras. The GAP follows the Western Maryland Railway and Pittsburgh & Lake Erie lines. The canal was dug between 1828 and 1850 to carry coal to tidewater through 74 lift locks, and closed after the flood of 1924; Justice William O. Douglas walked it to save it from becoming a highway. A railroad grade one half, a mule path the other, and both on one Great Allegheny Passage and C&O Canal Towpath map poster.