Solarapex. "The Gadsden Purchase Historical Marker." 19 November 2004. Photograph. Description: The historical marker is situated at a rest stop for Interstate 10, north of Casa Grande, Arizona, commemorating The Gadsden Purchase. Source: Own work. Camera location: 33° 02′ 31.09″ N, 111° 47′ 08.17″ W. Kartographer map based on OpenStreetMap.