The Williamstown and Delaware River Railroad was a railway company in the United States.

The Williamstown Railroad constructed a line between Williamstown, New Jersey, and Atco, New Jersey, which opened in 1872 and had a connection to the Camden and Atlantic Railroad near Atco.

The company went bankrupt in 1881 and in 1883 was acquired by Philadelphia and Reading Railroad interests.

The reorganized company was named the Williamstown and Delaware River Railroad, and incorporated on December 7, 1883.

[1] The Williamstown Railroad had planned to build west to Glassboro, New Jersey, but lacked the resources.