Dewmaine was an unincorporated African-American coal-mining community in Williamson County, Illinois. Today the area is almost completely non-residential and vacant land, though it now sits at the northern edge of Carterville. Its name is an amalgamation of Admiral Dewey and the USS Maine from the Spanish–American War. A post office was established at Dewmaine in 1901, and remained in operation until 1931. It is now served by the Carterville post office. Estimated population in 1958 was 50.