Chesapeake and Ohio Canal National Historical Park | LOCK 12

Upstream gate of Lock 12 of the Chesapeake and Ohio Canal

Upstream gate of Lock 12 of the Chesapeake and Ohio Canal


Lock 12 is located at Mile 9.3 on the Chesapeake and Ohio Canal towpath. It cannot be accessed by vehicle, so reaching it requires hiking or biking a half mile (one way) upstream from the closest parking area, Lock and Lockhouse 10. See the Locks and Lockhouses web page for an interactive location map.


Lock 12 is one of seven locks within a 1.1-mile span of the Chesapeake and Ohio Canal, all of which are appropriately known as the Seven Locks. It is unique in that its upstream gate is a drop gate and not a typical miter gate. A miter gate has two doors that meet at an angle pointing upstream. The pressure of the water keeps them shut naturally. A drop gate, on the other hand, is a single door that opens by falling in the upstream direction like a tailgate on a pick-up truck and closes by being hoisted back in place with mechanical gears. It cannot fall downstream because it rests against notches in the stone retaining walls of the canal.

Illustration of a drop gate

Illustration of a drop gate

Drop gate hardware on the upstream gate of Lock 12 on the Chesapeake and Ohio Canal

Drop gate hardware on the upstream gate of Lock 12 on the Chesapeake and Ohio Canal

Chains keep the drop gate of Lock 12 on the Chesapeake and Ohio Canal from falling forward and the notch in the stone wall keeps it from falling backward

Chains keep the drop gate of Lock 12 on the Chesapeake and Ohio Canal from falling forward and the notch in the stone wall keeps it from falling backward

The upstream gate was converted to a drop gate when the entire lock was lengthened ten feet on the upstream end so it could accommodate larger boats. I assume the C&O Canal Company figured that if a new gate had to be built anyway, might as well try out the drop gate technology. The longer boat idea never gained much ground, so only a few locks in this area were enlarged.

The downstream end of the lock was never modified, and the miter gate remained in place.

Downstream view from Lock 12 on the Chesapeake and Ohio Canal

Downstream view from Lock 12 on the Chesapeake and Ohio Canal

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Last updated on June 10, 2024
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