From CP-Cola (MP 38.4), where a line from York once trailed in across the river from the west, a Reading line once trailed in on the east side the center siding ends, the Columbia Secondary to Lancaster departs on the east side, with that extra track trailing into it, and there is a crossover, the double track, current-of-traffic, line with overall speed limit 40 mph on Track 1 (west) and 35 mph on Track 2 (east) continues south-southeast, along the east bank of the Susquehanna River, past detectors at Manor (MP 36.5), Washington Boro (MP 34.7), where it turns just south of due east, and Port (MP 33.7/39.7), where the former mileage is from Parkesburg via the erstwhile Atglen & Susquehanna Low Grade Line which once left to the east, while the latter is from Perryville via the Columbia & Port Deposit Railroad, on which the line now embarks, and the speed limit drops to 30 mph
This line runs through deciduous woods alongside the Susquehanna River, with several hydroelectric dams along this stretch of the river, past CP Cres (MP 38.3), where the double track reduces to single track, CTC, and the speed limit rises to 35 mph, Star Rock (MP 36.1), a detector at Safe Harbor (MP 33.6), where it turns southeast, CP-West Harbor (MP 33.2), where a 6,150 ft. west side siding starts, with speed limit 30 mph on the main and 10 mph on the siding, CP-Harbor (MP 31.9), where the siding ends, the line turns south, and the speed limit rises to 35 mph, a detector at MP 30.4, Pequea (MP 29.7), where there is a 30 mph speed restriction on the reverse curves to MP 29.0 as the line jogs southeast and then south again, CP-McCalls (MP 26.8), where a 26,900 ft west side siding starts, McCalls Ferry (MP 25.7), a turn south-southeast, still following the river bank, CP-Holtwood (MP 25.0), where there is a crossover and the speed limit drops to 30 mph, and CP-Midway (MP 21.7), where the siding ends and the speed limit rises to 35 mph.
The line continues past Fishing Creek (MP 20.3), Peach Bottom (MP 17.4), where a narrow-gauge line once ran in from the east and the line turns south, a detector at MP 17.2, reverse curves at MP 16, with speed restriction 30 mph, Williams Tunnel (MP 16.0), the Pennsylvania-Maryland state line (MP 14.7), Frazier Tunnel (MP 14.6), Wildcat Tunnel (MP 14.2), CP-West Pilot (MP 13.0), where a 6,500 ft. west side 10 mph siding starts, CP-Pilot (MP 11.6), where the siding ends and the speed limit rises to 40 mph, Conowingo (MP 10.0), a detector at MP 9.5, CP-West Rock (MP 7.4), where a 15,300 ft. west side siding starts and the speed limit drops to 30 mph, Rock (MP 6.4), where a branch once trailed in on the east side, Port Deposit (MP 4.7), CP-Tome (MP 4.5), where the siding ends, CP-Quarry (MP 3.2), where a 16,800 ft. east side siding starts, Minnick (MP 2.0), detectors at MP 1.8, Aikin (MP 0.8), where a CSX connector from their Philadelphia line at West Aikin trails in on the east side and the speed limit drops to 15 mph, and Perryville (MP 0.0), on the east side of the Susquehanna, where the Port Road (also known as the Columbia & Port Deposit branch), once part of the electrified territory of the Pennsylvania Railroad, joins the north side of the NEC through a 15 mph wye with the depot in the south vee of the junction.