Mojave (or Mohave) Desert, an arid region in southern California. It extends from the southern end of the Sierra Nevada range southeastward to the Colorado River, occupying some 20,000 square miles (52,000 km2). The Mojave is largely a barren region; landforms are mainly sandy plains, dry lake beds, and scattered low mountains. In or near the desert are Joshua Tree and Death Valley national parks and Mojave National Preserve. Large military installations, including Edwards Air Force Base, occupy much of the desert. Cities include Barstow, Lancaster, Palmdale, and Victorville.