Kankakee River State Park is an Illinois state park on 4,000 acres primarily in Kankakee and Will Counties, Illinois, United States. Originally, 35 acres of land was donated by Ethel Sturges Dummer for the creation of the state park in 1938. Another 1,715 acres was donated by Commonwealth Edison in 1956, which again donated more land in 1989. The islands of Smith, Hoffman, Langham, and Willow are all located inside the park on the Kankakee River.