Elsinboro Township is a township in Salem County, New Jersey, United States. As of the 2010 United States Census, the township's population was 1,036, reflecting a decline of 56 (-5.1%) from the 1,092 counted in the 2000 Census, which had in turn declined by 78 (-6.7%) from the 1,170 counted in the 1990 Census.
Elsinboro's first mention dates back to May 12, 1701, though it was also mentioned in records on November 28, 1676. The details and date of its original incorporation are unknown. The township was incorporated by an Act of the New Jersey Legislature on February 21, 1798, as one of New Jersey's original group of 104 townships.