In Deserts, Forests and Grasslands you learned that a desert is a dry place. The United States has four big deserts, all in the West and Southwest.
Key idea
The four big U.S. deserts are the Mojave (California and Nevada; Death Valley, Las Vegas, Joshua trees), the Sonoran (Arizona and California; saguaro cactus), the Chihuahuan (mostly in Mexico, reaching into New Mexico and West Texas) and the Great Basin (Nevada and Utah), a cold desert.
Why it works
Why is the West so dry? Storms come in from the Pacific. As the air rises over the Sierra Nevada and the Cascades, it cools and drops its rain and snow on the western slopes. By the time the air comes down the other side, it is dry. The land behind the mountains is in a rain shadow.
Worked example: Match the plant
The tall saguaro cactus with arms grows in which desert?
- Saguaros need warm winters with little frost.
- They grow in southern Arizona, around Phoenix and Tucson.
- That is the Sonoran Desert.
Answer: The Sonoran Desert.
Common mistake
Deserts are not always hot. A desert is defined by being dry. The Great Basin Desert is high and far north, so it has cold, snowy winters, yet it gets so little rain and snow in a year that it is still a desert.