Walpack Township is a township in Sussex County, in the U.S. state of New Jersey. As of the 2020 United States census, the township's population was 7, a decrease of 9 (−56.3%) from the 2010 census count of 16, which in turn reflected a decline of 34 (−82.9%) from the 41 counted in the 2000 census. Walpack Township was the smallest municipality by population and one of only four municipalities in New Jersey with a population under 100 as of the 2020 Census; it had the state's third-smallest population in the 2010 census, behind Tavistock and the now-defunct Pine Valley, both in Camden County.

Tavistock is a borough in Camden County, in the U.S. state of New Jersey. As of the 2020 United States census, the borough's population was 9, an increase of 4 (+80.0%) from the 2010 census count of 5, which in turn reflected a decline of 19 (−79.2%) from the 24 counted in the 2000 census. As of the 2010 Census it was the smallest municipality by population in New Jersey, with seven fewer residents than nearby Pine Valley, which had 12, while the 2020 census placed Tavistock as second-smallest by population, two more than Walpack Township, New Jersey, which had a population of 7.