Desert bighorn sheep establish two desert areas in southwestern Arizona to help preserve the desert bighorn sheep: Cabeza Prieta National Wildlife Refuge and the Kofa National Wildlife Refuge. In 1941, the San Andres National Wildlife Refuge in New Mexico was added. Desert bighorn sheep populations have trended upward since the 1960s when their population was estimated at 6,700-8,100. The upward trend was caused by conservation measures, including habitat preservation. In 1980, desert bighorn sheep populations were estimated at 8,415-9,040. A state-by-state survey was conducted a few years later and estimated the overall US desert bighorn sheep population at 15,980. The 1993 estimate of
Mojave Desert the Mojave Tribal Nation officially uses the spelling "Mojave"; the word is a shortened form of Hamakhaave, their endonym in their native language, which means 'beside the water'. The Mojave Desert receives less than of rain a year and is generally between in elevation. The Mojave Desert also contains the Mojave National Preserve, as well as the lowest and hottest place in North America: Death Valley at below sea level, where the temperature often surpasses from late June to early August. Zion National Park in Utah lies at the junction of the Mojave, the Great Basin Desert, and the Colorado