Hackensack is the most populous municipality in and the county seat of Bergen County, in the U.S. state of New Jersey. The area was officially named New Barbadoes Township until 1921, but has informally been known as Hackensack since at least the 18th century. As of the 2020 United States census, the city's population was 46,030, its highest decennial count ever and an increase of 3,020 (+7.0%) from the 2010 census count of 43,010, which in turn reflected an increase of 333 (+0.8%) from the 42,677 counted in the 2000 census.