Levittown is a hamlet and census-designated place in the Town of Hempstead in Nassau County, on Long Island, in New York. It is a suburb of New York City, located halfway between the villages of Hempstead and Farmingdale. As of the 2010 census, the CDP had a total population of 51,881, making it the most populous unincorporated CDP in Nassau …Levittown is a hamlet and census-designated place in the Town of Hempstead in Nassau County, on Long Island, in New York. It is a suburb of New York City, located halfway between the villages of Hempstead and Farmingdale. As of the 2010 census, the CDP had a total population of 51,881, making it the most populous unincorporated CDP in Nassau County and the second most populous CDP on Long Island, behind Brentwood.