Caldwell is a borough located in northwestern Essex County, in the U.S. state of New Jersey, about 16 miles west of New York City and 6 miles 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 from the 2010 census count of 7,822, which in turn reflected an increase of 238 from the 7,584 counted in the 2000 census.