Chesapeake and Ohio Canal National Historical Park | LOCK AND LOCKHOUSE 21

Downstream view of Lock and Lockhouse 21

Downstream view of Lock and Lockhouse 21


Lock and Lockhouse 21 are located at Mile 16.7 on the Chesapeake and Ohio Canal towpath. There is vehicle parking at the site. See the Locks and Lockhouses web page for an interactive location map.


Lock 21 on the Chesapeake and Ohio Canal is also known as Swain’s Lock, named after the last lockkeeper who lived here when the canal closed in 1924. The lockhouse in which he and his family lived is still standing. In addition to a yearly salary, Swain, like all men hired as lockkeepers, lived in the company provided lockhouse and had use of an acre of land for farming. Those who tended multiple locks got extra money per lock, up to two. The locks had to be very close together for the C&O Canal Company to assign multiple locks to one person.

Like many lockkeepers serving as employees when the canal closed, the Swains were never evicted, and family members continued to live in the house until 2006. They ran a boat rental and a refreshment stand to serve hikers and bikers passing by on the towpath. In March 2018, renovation on the house began, and two of the Swains who lived in the house attended the groundbreaking ceremony.

While such houses once stood at nearly all locks on the Chesapeake and Ohio Canal, very few survive today. Of those that do remain, most are not open to the public, at least not on any regularly scheduled basis. This makes Lockhouse 21 even more special because it can be rented for overnight stays by those wanting an authentic canal and lockhouse experience. The C&O Canal Trust maintains seven such houses for rent within the Chesapeake and Ohio Canal National Historical Park. See the Lockhouse Rentals web page here on National Park Planner for more information.

Each of the seven lockhouses available for rent represents a different time period. Lockhouse 21, though built in the early 1830, was outfitted with electricity, heat, and running water by the Swains, and modern heating and air conditioning was added during the renovation. It is now furnished as it might have been in 1916. The house has two bedrooms with enough beds, trundles, and cots for eight people. Keep in mind that no linens or pillows are provided other than comforters and mattress pads. I suggest bringing a sleeping bag if you have one.

Lockhouse 21 (aka Swain’s Lockhouse)

Lockhouse 21 (aka Swain’s Lockhouse)

Downstream view of the upstream gate on Lock 21

Downstream view of the upstream gate on Lock 21

Upstream view of the upstream gate on Lock 21

Upstream view of the upstream gate on Lock 21

Downstream view of Lock 21

Downstream view of Lock 21

Lock 21 is interesting because it has an intact sluice. All locks had them, but today many have been filled in with dirt or are covered in vegetation and hard to spot. In most cases, the sluice was just a rudimentary ditch that ran parallel to the lock. When the upstream gates were closed, the sluice allowed water to flow around the lock instead of backing up into a pool of excess water that could spill over the banks of the canal or put additional pressure on the lock gates. The water emptied back into the canal just past the downstream gates. The idea is similar to that of a spillway on a dam.

The sluice at Lock 21 is in plain sight, and you can even follow it all the way down to a canoe launch on the canal. Visitors are welcome to paddle the C&O Canal from Lock 23 on down to Georgetown. However, while most locks, including Lock 21, have gates in working order, paddlers cannot go through the locks and must instead portage around them.

Sluice of Lock 21

Sluice of Lock 21

Just upstream is the Swains Lock Campground for hikers and bikers and a small picnic area. This is the closest campground to Georgetown. If you are thinking you can camp here even if you are in a car, you are mistaken because vehicles cannot be left overnight at the Lock 21 parking lot without a permit.

Swains Lock Campground and Picnic Area

Swains Lock Campground and Picnic Area

If you find yourself hiking or biking upstream from Lock 21, you will pass the Washington Suburban Sanitary Commission water filtration plant. A dam has been built at this location, and a memorial has been erected along the towpath. These date to 1962 and have no historical significance or connection to the canal.

WSSC Water Filtration Plant memorial

WSSC Water Filtration Plant memorial

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Last updated on April 23, 2020
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