South Monroe is an unincorporated community and census-designated place in Monroe County, Michigan. The community is a part of Monroe Charter Township and borders Monroe to the southwest. The population was 6,370 during the 2000 census. The community is bisected by M-125, locally known as Dixie Highway. According to the United States Census Bureau, South Monroe has a total area of 2.4 square miles. The community uses ZIP code 48161—assigned to Monroe—and has the FIPS code 26-75140.