Mequon, Wisconsin, United States [City]; population was 18,885 in 1990; housing units was 6,470 in 1990; location is 43°14'N 87°59'W; land area is 46.19 square miles (29,559 acres); water area is 0.63 square miles (406 acres); FIPS code is 51150 [SourceCBP]