Stockton is a borough in Hunterdon County, in the U.S. state of New Jersey. The borough sits on the Delaware River at the western end of Amwell Valley. As of the 2020 United States census, the borough's population was 495, a decrease of 43 (−8.0%) from the 2010 census count of 538, which in turn reflected a decline of 22 (−3.9%) from the 560 counted in the 2000 census.