Leesburg is an unincorporated community and census-designated place (CDP)[5] located within Maurice River Township in Cumberland County, in the U.S. state of New Jersey.

Similar to Dorchester, the first settlers to the area were most likely Swedish, though a town was not established until 1795 when John Lee, an Egg Harbor shipwright, founded Leesburg.

In 1850 James Ward built a marine railway here to facilitate the repair of larger ships, which were attracted to Maurice River site because it was only six miles from the Delaware Bay.

Though Leesburg's economic base was primarily shipbuilding, two successful early twentieth-century industries were the Leesburg Packing Company, a cannery that seasonally employed 100 persons, and J. C. Fifield and Son, a fertilizer works.

Today the only evidence of these industries is WHIBCO Inc., a sandmining company whose administrative offices occupy the buildings of the former Del Bay Shipyard Bayside State Prison is located in Leesburg.