The first park land was given to the state by Marion County in 1937. Later, private purchases added to the area in 1952 and 1958. Ellen B. DeWitt gave a small tract in 1965 and the State Highway Division transferred the final acreage in 1968. The Santiam River was named for the Santiam Indians, a Kalapooian tribal group that held the surrounding territory at the time of Euro-American contact.