Back Creek is a 16.8-mile-long (27.0 km)[1] tributary of Conococheague Creek in south central Pennsylvania in the United States.[2]
The uppermost reaches of the creek, flowing through the Letterkenny Army Depot, are known as Rocky Spring Run[2] or Rocky Spring Branch.
Back Creek joins Conococheague Creek approximately 0.33 miles (0.5 km) below Williamson.[2]