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The C&O Canal Towpath Trail and Great Allegheny Passage

Lock #21 (Swain's Lock)

Camping, Point of Interest, Parking
Potomac MD
10700 Swains Lock Rd
Potomac, MD 20854
301-739-4200

Lock #21 (Swain's Lock) is located on the C&O Canal Trail, in Potomac MD

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Lock 21 (Swains Lock)
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Forum Discussions about Lock #21 (Swain's Lock)

Lock #21 (Swain's Lock) in Potomac
Joe Willmott from Columbia on 07/23/2026 04:03 PM:
I want to arrange a C&O history lecture on October 17 for a private group of 10-12 persons visiting from Ohio. Anyone interested in presenting this for an honorarium? Also need advice on a venue.

 
Cathy from Churchill from Churchill on 07/27/2026 01:32 AM:
Posting your question here is a good start. You might also check Facebook. There's at least one, and probably more, Facebooks groups devoted to the GAP/C&O, for example Great Allegheny Passage / C&O Canal Enthusiasts. Also, if you are interested in a particular location, try looking for local historic associations in that area, and reaching out to them. If they don't have "docents" who do that type of presentation on a regular basis they might have someone willing to put together a talk for your group on the history you are interested in.

 
Doug red runner from Westminster on 07/27/2026 09:31 PM:
You may also wanna try the Williamsport visitor center. the canal is divided up into sections for coverage ... I think they cover from D.C. to Williamsport.. 301-739-4200 or at least they may point you in the right direction

Lock #21 (Swain's Lock) in Potomac
Denbo from Louisville KY on 04/17/2025 04:20 PM:
What is the homeless person situation at Swains Lock h/b?

Lock #21 (Swain's Lock) in Potomac
Barry Davidson from Maplewood on 08/06/2020 05:17 PM:
Where is there free long term parking on the trail closest to georgetown? I want to do the whole thing all the way to pittsburgh and take the train back to DC. Then I'll ride to my car.

 
JM from Central Florida on 08/06/2020 08:04 PM:
I biked Pittsburgh to DC 2 weeks ago. I parked at Great Falls Tavern, MD (then biked to DC Reagan National Airport, rented a car, drove to Pittsburgh, dropped the car off in downtown Pittsburgh, rode to Point State Park and then back to my car at Great Falls). Parking at Great Falls Tavern is plentiful and free. If you alert the NPS either online or at the entry gate, you'll feel better about leaving your car.

I considered Amtrak, but recent info made me wonder how that would work out. It sounds as if the bike racks aren't currently being used, but bikes are laid down in the baggage cars. There have also been recent notices on the Amtrak site about possible bus transfers due to construction if the train got behind schedule by more than an hour. Too many unknowns for me. Good luck and enjoy the trails.

Lock #21 (Swain's Lock) in Potomac
jrush on 07/05/2019 01:13 PM:
Is this a free biker campsite?

 
John from Pittsburgh on 07/05/2019 10:22 PM:
Yes. All “hiker/biker” sites along the C&O are free. The GAP is a different story.

 
Rivnuts from Homestead, PA on 07/15/2019 11:47 AM:
While the Hiker/Biker (H/B) campsites along the C&O Canal Trail are free there are other campsites along the C&O that are not free such as at Spring Gap, 15 Mile Creek, Antietam, etc. While they may appear to be H/B sites they are generally larger and better maintained and hence why they require a reservation and fee.

There are free trailside campsites along the GAP Trail although they are not referred to as "H/B" sites. There are free camp sites at Connellsvile, Round Bottom, Cedar Creek Park and Dravo Cemetary.

Lock #21 (Swain's Lock) in Potomac
Lowell J Herschberger from Brooklyn on 08/17/2018 08:19 PM:
Is it safe to leave a car here for several days?

Lock #21 (Swain's Lock) in Potomac
Robert martin from Silverspring md. on 08/30/2013 09:47 PM:
Do I need a permit to camp. If so where do I get it.

 
Stillridng from Pittsburgh, PA. on 08/31/2013 09:52 AM:
This is a free campsite at mile marker 16. I think it has 5 to 7 sites available. Right next to the river, very nice.

 
vabiker23518 from Williamsburg, VA on 09/06/2013 10:00 AM:
It's been a few years ago, but I camped there and no permits were required.

Lock #21 (Swain's Lock) in Potomac
Mark Bottinick from Silver Spring on 06/11/2013 08:43 PM:
The email above should read "there is NO water at swain's lock" not "there is now water at Swain's lock."

No Water at Swain's Lock Campground
Swagman from LaGrange, GA on 03/17/2013 04:24 PM:
There is now potable water at Swain’s Lock. The water fountain device was removed when NPS removed the concessions stand next to the Lock 21. There is no water pump either. You’ll need to filter water from the canal or Potomac.