Upper Sioux Agency State Park contains the site of the Upper Sioux or Yellow Medicine Agency. The park was established in 1963 to preserve and interpret the remains of the old Agency site. The park covers 1,280 acres and offers diversity: open prairie knolls, bluffs, and cool, wooded slopes. From the vistas, visitors enjoy the trails which are ideal for horseback riding, hiking, skiing, and snowmobiling. The park also offers a huge sliding hill for winter fun.