In 1923, Mound City Group National Monument was established by a proclamation signed by President Warren G. Harding to preserve prehistoric mounds of "great historic and scientific interest." In 1980 Congress expanded the monument to add the nearby Hopeton Earthworks and authorized the investigation of other regional archaeological sites to determine their suitability for preservation. The National Park Service recommended adding four additional sites. In 1992, Hopewell Culture National Historical Park was established by a law that renamed Mound City Group National Monument. The Hopewell Culture National Historical Park now includes six other sites including Hopeton Earthworks, Seip Earthworks, High Bank Works, Spruce Hill Earthworks, and Hopewell Mound Group. (Click here to see a NPS website about these other locations.)
