Lock 64 2/3 at Mile 154.6 on the Chesapeake and Ohio Canal towpath (photo by Bob Marquart)

Lock 64 2/3 is located at Mile 154.6 on the Chesapeake and Ohio Canal towpath. It is not accessible by vehicle, so reaching it requires hiking or biking 1.6 miles (one way) downstream from the parking area at the Paw Paw Tunnel. See the Locks and Lockhouses web page for an interactive location map.

Lock 64 2/3 on the Chesapeake and Ohio Canal is one of three locks that are located on the downstream side of the Paw Paw Tunnel. It is a 1.6 mile hike or bike ride from the tunnel parking area, but since the towpath is mostly level, it’s an easy journey. If you want some serious exercise, you can take the Paw Paw Tunnel Hill Trail on the way too the lock and return through the tunnel on your way back. The trail goes over the mountain starting at the tunnel’s upstream entrance and comes out on the towpath .4 mile from the downstream entrance.

The tunnel and locks are located in an area of the Potomac River Valley known as the Paw Paw Bends. Over the course of six miles, the river zigzags three times and is flanked by rock cliffs. Cutting a canal into the rock along the river would have been next to impossible, so canal engineers had two choices. One, they could dam the Potomac at the downstream end of the Bends so the river could be made deeper and thus navigable at all times. Boats would leave the canal and travel directly on the river.

A second option was to create a nearly six-mile shortcut around the Bends by cutting through the interior. The only problem was that there was a mountain in the way. With an estimated cost of $33,000 and a completion date of two years, it was decided to tunnel through the mountain, a decision that nearly bankrupted the C&O Canal Company. Work began in 1836, and when the tunnel opened in 1850, twelve years behind schedule, it had cost $600,000. Funds actually ran out and no work was done from 1842 through 1847.

The C&O Canal Company planned to dig four locks between the downstream end of the Paw Paw Tunnel and the Potomac River, but only ended up needing three. Since the entire canal had been planned and the locks were already named, it was decided to skip the nomenclature for Lock 65 and just use the names Lock 62, Lock 63 1/3, and Lock 64 2/3 for the three locks.

By the time these locks were built, the C&O Canal Company was in financial trouble, plus it was difficult to get stone to the upper reaches of the canal. As a result, contractors were allowed to use whatever type of stone they could find, plus augment construction with wood. This combination of stone and wood is known as a composite lock. Composite locks began with Lock 58 and continued through Lock 71.

Lock 64 2/3 is unique in that some of the wood used to construct the retaining walls still exists. The wood has long since rotted away on most of the other composite locks.