Walpack Township is a township in Sussex County, New Jersey, United States. As of the 2010 United States Census, the township had a population of 16, reflecting a decline of 25 (-61.0%) from the 41 counted in the 2000 Census, which had in turn declined by 26 (-38.8%) from the 67 counted in the 1990 Census. Walpack Township was one of only four municipalities in New Jersey with a double-digit population as of the 2010 Census, and it placed third behind Tavistock (population 5) and Pine Valley (population 12), both in Camden County.
Walpack Township dates back to October 26, 1731, when it was first mentioned as Walpake in Hunterdon County. The area covered by the present-day township was set off to Morris County upon that county's creation in 1739, and became part of the newly formed Sussex County in 1753. As of April 15, 1754, Walpack's boundaries were defined as a "precinct". Walpack was formally incorporated as a township by an Act of the New Jersey Legislature on February 21, 1798. Portions of the township were taken to form Montague Township (March 26, 1759), Sandyston Township (February 26, 1762) and the now-defunct Pahaquarry Township in Warren County (December 27, 1824).
The current Walpack Township is named from a corruption of the Lenape Native American word "wahlpeck," which means "turn-hole," or an eddy or whirlpool. This word is a compound of two Native American words, "woa-lac" (a hole), and "tuppeck" (a pool).
New Jersey Monthly magazine ranked Walpack Township as its 18th best place to live in its 2008 rankings of the "Best Places To Live" in New Jersey.