When I started running, way back in 2000, my favorite trail was the Pennypack trail. Few of us would drive there from Fox Chase Cancer Center after work, and go for 3-5 mile run, depending on how much time we had. We run there many times, too many to remember each one separately. My best guess is that we started probably in July 2000.
Pannypack trail is probably the best place to go running in Northeast Philadelphia area. Driving north on the Pine Rd brings you straight to the park. Just before the Pine Road crosses Pennypack creek, there is a park entrance on the right and the trail head is at the far end of the parking lot. I am not sure know how long the trail is, but it seems on the map that it goes all the way to the Delaware river. The longest I ever run there was 6 miles round trip (so 3 miles down the trail, then back the same way). I do not have any pictures, or GPS tracks, but I am including this Google Earth view. The parking lot is in the middle and the trailhead is just to the right.