The Pennsylvania RR Pomeroy Branch was built in 1869 as the Newark & Pomeroy RR. The surviving sections succeeded through the Pennsylvania RR, Penn Central, and then Conrail. The line extended from Pomeroy, PA, on the main between Philadelphia and Harrisburg, to Buck Run, Doe Run, Chatham, Avondale (were it intersected the PRR Octoraro Branch), then to Landenburg (where it intersected the B & O Landenburg Branch), then into Delaware to Newark, Davis, Porters, Raybolt and finally to Delaware City on the Delaware River. The Branch intersected all the major lines coming SW out of Wilmington, DE. The only remaining active portions are from Davis to Porters to Raybolt, and this section is used to serve industries in the area.

The section from Pomeroy, PA, to the Delaware state line was abandoned in 1937. The section from the Delaware state line to Newark was abandoned in 1939. Some remaining trackage in Newark, DE, that was serving local customers was abandoned and pulled up in 1984.