Lock

This is a detail on one of 74 canal locks (most now in disuse) along the C&O canal.

The C&O (Chesapeake & Ohio) Canal runs 187 miles, parallel to the Potomac river, from Maryland to DC. It operated between 1831 and 1924, as a way to carry goods and mail downstream. A foot path runs alongside it, which is heavily used by Washingtonians to walk, run, bicycle and horseback ride.