@KlasfeldReports some of my favorites: VA - Prince William National Forest has some great hiking /running trails. Just off the main entrance, Pyrite mine trail ~ 7 miles but can add additional miles with a few modifications. Fountaihead Park/Bull Run Occoquan one-way 6 miles (12 miles total with 1400’ elevation). Just north of DC in Maryland-Seneca Creek or Ridge trails. Both around 13 milers total.