Clear Lake Site in Sand Ridge State Park in central Illinois preserves evidence of Indigenous occupation from 500 B.C. to A.D. 1500, making it one of the region’s important multicomponent archaeological sites. Used by Early Woodland, Havana Hopewell, and Mississippian peoples, it contains a village area and two burial mounds that reflect long-term settlement and ceremonial use. Excavations begun in 1932 and later work by George and Ethel Schoenbeck recovered 24,000 pottery shards representing every pottery type found in Central Illinois. These discoveries made the site a key reference for studying regional ceramics and cultural change, and it was listed on the National Register of Historic Places in 1978.