South Hackensack is a township in Bergen County, New Jersey, United States. As of the 2010 United States Census, the township's population was 2,378, reflecting an increase of 129 from the 2,249 counted in the 2000 Census, which had in turn increased by 143 from the 2,106 counted in the 1990 Census.South Hackensack was formed as a township by an act of the New Jersey Legislature on November 15, 1935, replacing Lodi Township, based on the results of a referendum held November 5, 1935, which passed by a margin of 309 to 15. The township's name derives from its location relative to Hackensack.