Clifton is a city in Passaic County, New Jersey, United States. As of the 2010 United States Census, the city had a total population of 84,136, retaining its position as the state's 11th-largest municipality, as the population increased by 5,464 from the 78,672 counted in the 2000 Census, which had in turn increased by 6,930 from the 71,742 counted in the 1990 Census.Clifton was incorporated as a city by an act of the New Jersey Legislature on April 26, 1917, replacing Acquackanonk Township, based on the results of a referendum held two days earlier. Clifton is listed under five different ZIP Codes.