Caldwell is a borough located in northwestern Essex County, in the U.S. state of New Jersey, about 16 miles (26 km) west of New York City and 6 miles (9.7 km) north-west of Newark, the state's most populous city. As of the 2020 United States census, the borough's population was 9,027, an increase of 1,205 (+15.4%) from the 2010 census count of 7,822, which in turn reflected an increase of 238 (+3.1%) from the 7,584 counted in the 2000 census.

Essex County is located in the northeastern part of the U.S. state of New Jersey, and is one of the centrally located counties in the New York metropolitan area. As of the 2020 census, the county was the state's second-most populous county, with a population of 863,728, its highest decennial count since the 1970 census and an increase of 79,759 (+10.2%) from the 2010 census count of 783,969. The county is part of the North Jersey region of the state.