Upper Sioux Agency State Park is a Minnesota state park on the Minnesota River, south of Granite Falls. It preserves the site of the historic Upper Sioux Agency (or Yellow Medicine Agency), which was destroyed in the Dakota War of 1862. The agency site was listed on the National Register of Historic Places in 1970 for having state-level significance under the themes of archaeology, architecture, education, and social history. Chief Walking Iron Mazomani, a leader of the Wahpetonwan (Dwellers in the Leaves) Dakota tribes who was killed during the 1862 Dakota War's Battle of Wood Lake, is buried at this location.