Millville is a city in Cumberland County, in the U.S. state of New Jersey. As of the 2020 United States census, the city's population was 27,491, a decrease of 909 (−3.2%) from the 2010 census count of 28,400, which in turn reflected an increase of 1,553 (+5.8%) from the 26,847 counted in the 2000 census.

Cumberland County is a coastal county located on the Delaware Bay in the Southern Shore Region of the U.S. state of New Jersey. As of the 2020 census, the county was the state's 16th-most-populous county, with a population of 154,152, a decrease of 2,746 (−1.8%) from the 2010 census count of 156,898. Its county seat is Bridgeton. Cumberland County is named for Prince William, Duke of Cumberland. The county was formally created from portions of Salem County on January 19, 1748. The county is part of the South Jersey region of the state.