Clemson Island Prehistoric District in Pennsylvania centers on a 123-acre island accessible only by boat and preserves a rare mound-and-village complex within three archaeological loci. Especially important for evidence of a transitional Middle Woodland to Late Woodland community dating to about 900 to 1100 A.D., the island also shows a far longer span of human presence, from the Early Archaic period around 6,900 B.C. into the 18th century. Excavation of the mound in May and June 1929 drew formal archaeological attention to the site. Owned by Pennsylvania since 1965, the island is managed as a wildlife preserve and improvement area.