Swan Island Site in Crawford County, Illinois, lies on a sandstone ridge in the Wabash River flood plain and preserves a shell midden with evidence of Late Archaic occupation. It was inhabited by people of the Riverton culture, a group tied to the central Wabash Valley and known for distinctive tool-making methods. Archaeologists identified the site in the 1950s, and excavations began in 1961 under Dr. Howard Winters of the Illinois State Museum. By 1978, it was one of only three known Riverton culture sites, and its significance was recognized with its listing on the National Register of Historic Places.