Bethlehem Township is a township in Hunterdon County, in the U.S. state of New Jersey. It is part of the New York metropolitan area. As of the 2020 United States census, the township's population was 3,745, a decrease of 234 (−5.9%) from the 2010 census count of 3,979, which in turn reflected an increase of 159 (+4.2%) from the 3,820 counted in the 2000 census.

Hunterdon County is a county located in the western section of the U.S. state of New Jersey. At the 2020 census, the county was the state's 18th-most populous county, with a population of 128,947, its highest decennial count ever and an increase of 598 (+0.5%) from the 2010 census count of 128,349, which in turn reflected an increase of 6,360 (5.2%) from the 121,989 counted in the 2000 census. Its county seat is Flemington. The county is part of the Central Jersey region of the state.