[photos by Gary, junction with Appalachian Trail. Segment here is along an old woods road, but 2/3 of the trail is single-track and mostly runnable]
The trail is located in the Michaux State Forest, just a couple miles north of Caledonia State Park. PA Department of Conservation Natural Resources (DCNR) trail link with map is here.
The trail is like a flattened oval, with a spur trail located at each end to reach, respectively, the Appalachian Trail to the north, and Birch Run Road to the south, as it runs beside Long Pine Run Reservoir. DCNR lists its length at "approximately 4 miles" but I am not certain whether that includes both spur segments.
The trail has a short segment along a stream, some cool rhododendron "tunnels," plus some good views once you gain the 1900'+ ridgetop. Enjoy!
Center right = Rocky Knob, which the trail skirts, and is a tempting bushwhack to the summit; Long Pine Run Reservoir also visible
Large white pine (4' diameter trunk)