Monessen, Pennsylvania, United States [City]; population was 9,901 in 1990; housing units was 4,902 in 1990; location is 40°9'N 79°53'W; land area is 2.90 square miles (1,858 acres); water area is 0.15 square miles (99 acres); FIPS code is 50344 [SourceCBP]