That lock keeper's house........is at the very se corner of President's park...............the park, including the Ellipse..........which is directly south of the White house..........


Thus completed in 1833 and known as the C&O Branch Extension, DC's canal connection into the C&O began at the Rock Creek Basin and followed 27th Street down until it connected into the Washington City Canal at 17th and Constitution Avenues.

Image from the National Park Service.

Someone was going to have to collect the tolls and keep the records, so a Lockkeeper's House was built at 17th and Constitution. Owned today by the National Park Service, the Lockkeeper's House is one of the last reminders that a canal ever flowed through DC. A small federal style house built of fieldstone and measuring 30 feet wide and 18 feet deep, the Lockkeeper's House originally sat 40 feet west and 10 feet north of its current location, but was moved in the 1930′s to widen 17th Street.
According to some reports, the lockkeeper and his 13 children lived in the building. Otho Swain, a man born on a canal boat in 1901, whose father was a boatman and locktender and whose grandfather helped build the C&O, related this story:

My grandfather, he had boated coal down Constitution Avenue. There used to be a canal that crossed the Potomac there, and there's a little stone house still standing on the corner of 17th and Constitution Avenue. It was a lock house. My grandmother lived in that lock house, and that's where my grandfather met her.

The Lockkeeper's House was given to the National Park Service at the beginning of the 20th century during the construction of Potomac Park. For a time it was used as a "public comfort station", but today NPS uses it as storage.