Fairfield is a township in far northwestern Essex County, in the U.S. state of New Jersey. As of the 2020 United States census, the township's population was 7,872, an increase of 406 (+5.4%) from the 2010 census count of 7,466, which in turn reflected an increase of 403 (+5.7%) from the 7,063 counted in the 2000 census. Fairfield was the least densely populated town in Essex County in 2020.

Essex Fells is a borough in Essex County, in the U.S. state of New Jersey. As of the 2020 United States census, the borough's population was 2,244, an increase of 131 (+6.2%) from the 2010 census count of 2,113, which in turn had reflected a decline of 49 (−2.3%) from the 2,162 counted at the 2000 census.