The assessment report and accompanying geodatabase is designed to give the managers and planners of the City of Rocks National Reserve (CIRO) a better understanding of the natural resources within the Research Natural Area (RNA). Assessment of the natural resources was accomplished by conducting literature reviews, evaluating existing data, and collection of new data. The CIRO was created November 18, 1988, by Public Law 100-696, Arizona-Idaho Conservation Act of 1988. This act drew a 22 mile boundary around lands owned or managed by the USDA Forest Service (USFS), Bureau of Land Management (BLM), Idaho Department of Parks and Recreation (IDPR), and private individuals. After the approval of the 1994 City of Rocks National Reserve Comprehensive Management Plan, the Park Service officially transferred on-site management of the reserve to IDPR on May 2, 1996.