The deserts are home to a sociocultural and historical "Old West" collection of legends, districts, and communities, and they also form a popular tourism region of dramatic natural features and recreational development.

The Colorado Desert region encompasses approximately 7 million acres (2,800,000 ha), reaching from the Northwest Mexico border region in the south to the higher-elevation Mojave Desert in the north and from the Colorado River in the east to the Laguna Mountains of the Peninsular Ranges in the west.

The Great Basin Desert exists because of the "rainshadow effect" created by the Sierra Nevada of eastern California.

When prevailing winds from the Pacific Ocean rise to go over the Sierra, the air cools and loses most of its moisture as rain.

By the time the winds cross over the mountains and sweep down the far side, they are very dry and absorb moisture from the surrounding area.

[10] The driest spot in California is Death Valley, which averages 1.5 inches (38 mm) of precipitation per year.

Other common plants of the Mojave Desert include creosote bush, blackbrush, greasewood and saltbush.

[5]: 413  The Colorado Desert hosts saguaro cactus, Sonoran creosote bush, and Salton Sea saltbush.

Jedediah Smith travelled through the Great Basin and Mojave deserts in 1826, finally reaching the San Gabriel Mission.

[15][16] John C. Frémont explored the Great Basin, proving that water did not flow out of it to the ocean, and provided maps that the forty-niners used to get to California.

Badwater Basin, the lowest point in the United States lies within Death Valley National Park.