The Interior Northwest DC Trail Loop is not an official name, nor is it an official loop per se. There are many extensions and variations on this circuit, so this particular route description is by no means definitive. Nevertheless, it is a useful guide for assembling a route that makes use of the varied terrain and trail systems that run throughout Northwest DC.
Taking the C&O Towpath beneath the Key Bridge in Georgetown DC as the starting point, runners should go west on the Towpath for almost a mile. Just before a mile elapses, on the left of the towpath, there will be a large set of concrete steps that descend downward to the Capital Crescent Trail. Runners should descend these steps, but at the bottom, they should head to the right, beneath the Towpath itself, so that they will emerge on Canal Road and can connect to the Glover-Archbold Trail just slightly to the west. Runners should run this trail north to its end at Massachusetts Avenue NW, at which point they will connect to the Massachusetts 39th Trail, which they will follow to Upton Street NW.
From that point, follow Upton Street east, across Wisconsin Ave NW, to Reno Road. Turn right on Reno, and follow it to the Melvin C Hazen Trail, which runners can run to Connecticut Avenue NW. After crossing Connecticut Ave—please cross safely at a traffic signal—the Hazen trail continues downward through a tight ravine into Rock Creek Park. At the bottom of the Hazen Trail, runners can turn south on the Rock Creek Trail to return to Georgetown (ultimately via the sidewalk beneath the Whitehurst Freeway at the southern portion of the Rock Creek Trail). Approximate Distance: 10 miles