Enola Yard was constructed by the Pennsylvania Railroad in 1906, with two humps. The westbound yard has 20 reception tracks, (25 cars each) and 25 classification tracks (110 cars each, thus acting as their own departure tracks). The eastbound yard had 21 reception tracks (90 cars each) and 17 classification tracks (70 cars each). Overall, the yard could hold 10,705 cars. The yard was rebuilt, with automatic retarders, in 1938 (eastbound, to 15 reception and 33 classification tracks)) and 1944 (westbound, to 16 reception tracks and 35 classification tracks). Volume rose from 7000 cars per day (5000 humped) in 1906 to 11,207 per day in 1939 and 14,100 per day in 1941. The yard was expanded again after WWII (longer classification tracks, 144 cars each).
Enola was largely bypassed by the traffic routings adopted by Conrail after 1976, and especially after electric freight operations ended in 1983. The eastbound hump also closed in 1983, and the westbound in 1993. After Norfolk Southern took over in 1999, it resumed some use of Enola, as a flat classification yard, with four daily manifest trains using the yard.
The yard is located on the west side of the Susquehanna River, across from Harrisburg, extending southward from the west end of the Rockville Bridge.