This short branch left the former Pennsylvania RR line from Hanover, PA to Frederick, MD at Keymar, just south of where the PRR passed under a Western Maryland bridge. The short branch to Union Bridge was likely abandoned in the 1960s; the remaining former PRR and WM routes are now operated as Maryland Midland (MMID).
The branch to Union Bridge followed the north side of Little Pipe Creek for most of its distance. At the far eastern end it rose out of the creekside area and ended at a large cement factory still in operation. Very little of the right of way can be located today (2003).