This abandoned railway line between Atco and Mullica Hill was first operated by the Williamstown Railroad, between Atco and Williamstown, in 1873. The WRR began grading further westward out of Williamstown with intent to reach Glassboro, but fell into financial hardship, and was subsequently purchased by the Philadelphia and Reading Railroad in 1883, who renamed the WRR as the Williamstown and Delaware River Railroad.
The W&DR continued the WRR's vision by actually completing the line to Glassboro in 1883, with a final extension to Mullica Hill in 1887. During this same year, the P&R merged the W&DR into another of their subsidiaries, the Atlantic City Railroad. In 1933, the ACRR became part of the Pennsylvania-Reading Seashore Lines.
Just as it was constructed, this railway line was abandoned in stages, starting in the 1940s, with a final abandonment taking place in the 1980s.