This is one of my favorite runs these days: Lancaster Junction Trail and Auction Road.
Start from the trail head, which is the Salunga Park and Ride, near Spooky Nook Sports. There is a public restroom there, but only open during the summer.
Head down the trail, and at the first road crossing, turn left off the trail and get on Shenck Road. Follow that to the covered Bridge. Go through the covered bridge, then turn right onto Auction Road. Follow this the whole way around (slight jog at Colebrook, just keep going the same direction) until the railroad tracks, which is the other end of the trail. Get back on the trail and bring it home.
The run has a couple of negatives:
1. Many people walking dogs on the trail.
2. Shoulders on the roads are not always great, but cars are infrequent.
3. The route is difficult to shorten or lengthen.
But all things considered, this is my go-to run these days. If you’re in Lancaster, you should give it a try.