Not so long ago, I suggested that DDOT look into using the old Jewett Street ROW from Connecticut Avenue to Klingle Road as a new trail. That trail would serve as a connection between Conn Ave and the under-construction Klingle Valley Trail.
That idea took on more relevance when the Adams Morgan Vision Framework came out and more relevancy when the Zoo announced they would be closing their gates more often. But after some digging, I realize that this is going to be harder than I thought.
It's unclear to me when the road was closed, or it it was even ever opened. Some maps, especially those from before 1940, show the road, but the only USGS maps I could find it on were from 1932 or earlier, and then they show it only as a light dashed line or narrow line. It's also not clear that the road circled is Jewett Street, since one document from 1920 calls it the "unnamed street running parallel with Connecticut Avenue."
In the late 1990's - as part of the lead-up to building the Kennedy-Warren's south tower and parking garage in 2002-2004 - the Klingle Corporation offered to facilitate the "formal closure of the portion of Jewett Street between the Kennedy-Warren and the National Zoo." At the time it was described as "a partially built public street" or "unbuilt" and in the legislation to close it, there was the claim that the road "has never been built or used as a public street." Regardless of what it was called, whether it was ever a road or not and if so when it was removed, legislation to close it passed in 2004.
As a result of that formal closure the majority of land, approximately 42 feet in width, was transferred to the Zoo "to assure that the forest cover will be protected in this area." A minor portion of the Jewett Street right-of-way, the “Klingle Valley Rehabilitation Area”, was transferred to the National Park Service for the purpose of straightening out the Klingle Valley boundary. A permanent fence was then constructed along the new boundary. So most of the ROW now belongs to the Zoo as the "Tree Preservation Zone" and some of the rest to NPS. DC no longer owns the ROW - if they ever did.
But... the ROW was 50 feet wide and the zoning commission order doesn't say who the other 8 feet now belongs to. I suspect it is the Kennedy Warren. But even if it does belong to DC, that still isn't really wide enough for a formal MUT. There is plenty of space between the zoo and the Kennedy-Warren (in the Tree Preservation Zone) for a trail, but permission will be just the first issue in building one.
In addition to ownership issues and the fence, the main issue is the topography itself. I don't know if it was the construction of the Zoo parking lot or the Kennedy Warren expansion, but nothing remains of a graded connection from Conn Ave to Klingle Road - if ever there was one.
These photos don't do it justice, but the transition from the Connecticut Avenue area down to the Klingle Valley Trail involves a pretty steep drop off.
Considering the topography and ownership issues, it MIGHT be possible to build a hiking trail through this area that connects Conn Avenue to Klingle Valley Trail - and even that would likely require moving the fence - but I think a bike trail is going to be too difficult at this point.