Penns Grove Secondary is a rail freight line in the Delaware Valley in the southwestern part of New Jersey.

Part of Conrail's South Jersey/Philadelphia Shared Assets it runs for approximately 20 miles (32 km) between its southern terminus at Penns Grove and Woodbury at the north where it joins the Vineland Secondary about 8.5 miles (13.7 km) south of Pavonia Yard in Camden.

Located within Gloucester County and Salem County, the Penns Grove Secondary serves industries and distribution facilities in the corridor along the east bank of the Delaware River and with spur lines to Pureland Industrial Complex and maritime facilities, including the Port of Paulsboro, and the Paulsboro refinery where rail interchange is provided by SMS Rail Lines.

It then passes through Thorofare, West Deptford Township, Paulsboro, Gibbstown, Repaupo, Bridgeport, Pedricktown, and Penns Grove.

[8] New infrastructure at the Port of Paulsboro includes the construction of a rail crossing, turnouts, and 11,000 feet (3,400 m) of track with a link to the Penns Grove Secondary and a balloon loop for dockside accessibility.

Of the four cars that fell into the creek, one was punctured, releasing 23,000 US gallons (87 m3; 19,000 imp gal) of highly toxic vinyl chloride,[18][19][20] which required an evacuation in the region and Paulsboro school lock-downs.

Normally, between March 1 and November 30 the bridge is left in the open position for maritime traffic and closed when trains approach.