Final answer:
The American Southwest, including parts of Texas, New Mexico, and Arizona, lies mainly in a desert climate region, characterized by arid conditions, low rainfall, and high sunlight exposure. The Great Basin, Mohave, and Sonoran deserts also contribute to the arid regions of the U.S.
Step-by-step explanation:
The area of the United States that lies mainly in a desert climate region is primarily found in the American Southwest. This region includes states such as Texas, New Mexico, and Arizona. The Southwest is characterized by arid conditions, receiving low rainfall and a high amount of sunlight throughout the year. Particularly western Texas and states like New Mexico and Arizona are known for these arid climates. Water conservation projects are essential for supporting major metropolitan centers in these regions because of the scarcity of water caused by the desert conditions.
Another notable desert region in the United States is the Great Basin Desert, which is a cold desert that experiences freezing temperatures during the winter. Deserts like the Mohave and Sonoran are also found within the U.S. and are located on the lee side of mountain ranges, which creates a rain shadow effect, further contributing to the arid climate.