Essex Fells is a borough in Essex County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 2,113, reflecting a decline of 49 from the 2,162 counted in the 2000 Census, which had in turn increased by 23 from the 2,139 counted in the 1990 Census.Essex Fells was incorporated as a borough by an act of the New Jersey Legislature on March 31, 1902, from portions of Caldwell Township. In 1981, the borough was one of seven Essex County municipalities to pass a referendum to become a township, joining four municipalities that had already made the change, of what would ultimately be more than a dozen Essex County municipalities to reclassify themselves as townships in order take advantage of federal revenue sharing policies that allocated townships a greater share of government aid to municipalities on a per capita basis. Effective January 1, 1992, it again became a borough.