The Great Basin Desert, the largest U. S. desert, covers an arid expanse of about 190,000 square miles and is bordered by the Sierra Nevada Range on the west and the Rocky Mountains on the east, the Columbia Plateau to the north and the Mojave and Sonoran deserts to the south.
This is a cool or “cold desert” due to its more northern latitude, as well as higher elevations (at least 3,000 feet, but more commonly from 4,000 to 6,500 feet). Precipitation, generally 7-12 inches annually, is more evenly distributed throughout the year than in the other three North American deserts. Winter precipitation often falls as snow.
Playas are a conspicuous part of this desert, due to its recent geological activity. In notable contrast to the other three deserts, Great Basin vegetation is low and homogeneous, often with a single dominant species of bush for miles. Typical shrubs are Big Sagebrush, Blackbrush, Shadscale, Mormon-tea and greasewood. There are only occasional yuccas and very few cactus.
The Colorado Plateau, centered in northeastern Arizona, and including the adjacent Four Corners region of Utah, Colorado and New Mexico, is sometimes included in the Great Basin Desert, sometimes considered a separate desert — the Navajoan — and sometimes not considered a true desert. The Plateau includes large barren areas, spectacular geological formations, more juniper and pinyon trees and generally higher elevations.