This route is still shown as "active" on atlases. The rails through much of Chambersburg have been removed, but the rest of the track east to near Shippensburg is in place, though there is little rail traffic. The line was single track in the Chambersburg area, but double track further east.
This route was part of Western Maryland's portion of the "alphabet route", where it participated with several regional railroads to provide competition to the PRR and NYC between Chicago and the New York area. This particular segment connected with the Reading just west of Shippensburg.
This line likely fell into decline after the series of mergers in the east (Reading into Conrail; WM into B&O and the Chessie/CSX), where there would be little need for interchange.
Side note: the Letterkenny Army Depot, near Culbertson, PA (along Pa. Rte. 433) has many rusted sidings on the property, with several stored hopper cars and passenger cars visible from the highway.