1 definition found neillsville - U.S. Gazetteer (1990) : Neillsville, WI (city, FIPS 55800) Location: 44.56042 N, 90.59089 W Population (1990): 2680 (1199 housing units) Area: 7.0 sq km (land), 0.1 sq km (water) Zip code(s): 54456