From the junction with the CSX line from Winchester, and NS line from Front Royal, at Hager (MP 74.8), the Hagerstown Secondary heads northeast, single track, Direct Control System, maximum speed 10 mph, past the start of an additional 8,550 ft. Running Track on the east side at South Switch Running Track (MP 74.6), Hagerstown (MP 74.2), the end of the Running Track and the flat crossing with the CSX Lurgan sub., at Town (MP 73.7), after which the maximum speed rises to 40 mph, heading north, past North Junction, wehre the stub of a former B&O line trails in from the south, on the east side, Maugansville (MP 70.5), the border between Maryland and Pennsylvania (MP 68.2), a detector at "Mason Dixon" (MP 68.1), Milnor (MP 65.7), and Greencastle (MP 63.3), where it edges just east of due north, past Green (MP 63.0), Marion (MP 58.9), where an erstwhile line form Mercersburg once trailed in on the west side, Ken (MP 54.8), a connection and crossing with the CSX Lurgan sub., and 13,600 ft. west-side siding, at Chambersburg (MP 51.6), turning northeast past Sam (MP 50.3), a detector at "Scotland" (MP 47.2), Scotland (MP 47.0), a location wehre an erstwhile branch once turned away south-southeast, Waynesboro Junction, Burg (MP 43.4), MP 42.0, where the maximum speed drops to 30 mph, and the junction with the south side of the Lurgan Branch at CP-Ship (MP 40.4), where the former PRR line once continued north-northeast to Enola Yard.
From the end-on junction with the CSX Lurgan sub. at CP-Lurgan (MP 42.4), the former Reading line heads curvily east-northeast, single track, Rule 261, maximum speed 10 mph, past MP 40.9, where the maximum speed rises to 40 mph, the junction (20 mph on the junction) with the Hagerstown Secondary, on the south side, and start of Two Main Tracks, Rule 261, at CP-Ship (MP 40.1), the resumption of single track, Rule 261, at CP-Lees Cross Roads (MP 36.3), Greythorne (MP 33.6), Hays Grove (MP 32.0), Longsdorf (MP 30.2), Huntsdale (MP 28.3), a detector at "Moors Mill" (MP 27.0), Barnitz (MP 23.4), Mt. Holly Spring (MP 22.0), the junction with the Gettsyburg Railroad, trailing in on the south side (and its former Reading incarnation formerly continuing north), and start of an 11,140 ft. south-side Controlled Siding (30 mph on the siding) at Carlisle Junction/CP-Carl (MP 21.1), and the end of the Controlled Siding at CP-Spring (MP 19.4).
The line turns curvily east, with a 35 mph speed restriction, from MP 18.5 to MP 17.0, past Boiling Springs (MP 17.4), Brantsville (MP 13.9), a line from Dillsburg trailing in from the south at D&M Junction, Grantham (MP 10.2), and Bowmansdale (MP 8.9), turning north-northeast, past a detector at "Rossmoyne" (MP 4.5) and the start of double track, current-of-traffic (Rule 251) at CP-Ross (MP 4.5)and east-northeast, past the junction with the Camp Hill Connector, and crossover, at Camp Hill (MP 2.7), and bridging over the Enola Branch, the Susquehanna River, and the Amtrak Keystone Line, to the junction with the south side of the former Conrail Harrisburg Line at CP-Capital (MP 0.0).