It is a rail trail that goes 11 miles in Pennsylvania and 22 miles in Marryland. New Freedom which is near the Mason Dixon line is the highest point. Everything else goes down hill basically from there to each end. You can do the whole trail end to end and back to where you started in about 4 1/2 hours.
How to get there:
Route 83 to exit one and head west on 851/Forrest Avenue. You will go through some stop lights when you hit the Susquehanna Trail/ Main street Shrewsburry. At that stop light you can go straight and stay on 851 West till you run into the town of Railroad. There is a parking lot there and you can't miss the Rail Trail. Back to the stop light you can go left on the Susquehanna Trail till the next stop light and go right on Constitution Ave. You will
hit a stop sign which will be Main street in New Freedom make a right and you will run across the Rail Trail and a few resturants and bike shop.