Decent options I have tried are across the bridge into the Discovery District, through and around University Park and south on the Trolley Trail past Hyattsville and on the Anacostia Trail (which is an extensive trail network)
My favorite run around here which has become my go to run and pretty much the only one I am doing these days is north on the Trolley Trail to Lake Artemesia.
Lake Artemesia is beautiful and the entire route only one major road needs to be crossed and the entire rest of the run is on biking/running trails.
That route is here: (starting from the back trail entrance of Riverdale Park Station)
It's almost exactly 1.5 miles out to the lake and 1.5 miles around the lake then 1.5 miles back home.
The 1.5 miles both out and back on the Trolley Trail is flat and scenic:
There are surprisingly few people on this trail considering how nice it is.
Then once you get to Lake Artemesia you have 1.5 miles of this:
The trail system down at the Anacostia Trail is the only thing that even comes to this run around this area and currently you have to run along Route 1 for a bit to get from the Trolley Trail to the Anacostia Trail so it's a higher stress run since they are not connected. As I posted a year ago eventually those will be connected, but not until 2020. That article is HERE.
Anyway if you live in Riverdale Park Station or even University Park, Calvert Hills or Hyattsville try out this Lake Artemesia run route!
2/9/20 update:
Here is another running route that was submitted in the comments by a reader:
2/9/20 update:
Here is another running route that was submitted in the comments by a reader:
