File:2021 Sivan Vahki, Casa Grande Ruins, Under The Olmsted Shelter.jpg
President Benjamin Harrison proclaimed the site to be Casa Grande Reservation on June 22, 1892, becoming the first prehistoric and cultural reserve in the US. President Woodrow Wilson then designated it a national monument on August 3, 1918. The monument is administered by the National Park Service and was added to the National Register of Historic Places in 1966.