UPDATE: GoDCer Jerry has correctly pointed out that this is not the Aqueduct Bridge. The National Archives has mislabeled this and it’s actually the Pennsylvania Ave. bridge over Rock Creek. You can see it here. I know leave you to the rest of this incorrect post.
The bridge no longer exists and was dismantled in the 1920s, but a small part still stands on the D.C. side. This part of the bridge is crossing the canal, and is approximately where Key Bridge hits M St. today.
[Click image for larger, high-quality version.]
Source: Flickr user usnationalarchives