Apple River Canyon State Park is an Illinois state park on 297 acres in Jo Daviess County, Illinois, United States. The park was begun with land purchased by the state in 1932, as a result of a prolonged campaign led by botanist Herman Silas Pepoon; with additional acquisitions since, 1,907 acres of land have been preserved to protect much of an 8+1⁄2-mile long canyon on the Apple River.