The North American Deserts are made up of four desert regions: the Great Basin, the Mojave, the Sonoran, and the Chihuahuan. Each are influenced by different temperatures, elevations, and the timing and quantity of rainfall. Studying the obvious and subtle differences between these ecological regions is one of the great delights of desert travel.

Great Basin Desert
Centered over the state of Nevada, but continuing into portions of California, Oregon, Idaho and Utah, this desert is located between the Sierra /Cascade Mountains on the west and the Rocky Mountains on the east. The Great Basin is actually not a single basin, but a series of basins and often substantial mountain ranges many over 10,000 feet. This is our most northern desert, with most basins over 4,000 feet. It is considered a cold desert.

Precipitation, much of it snow, averages between four and eleven inches. The majority falls during late winter and early spring, produced by the same storm systems that bring rains to the Pacific Northwest. These storms have to rise over the massive Cascade Range, where most of the rainfall is forced out of the clouds. The Great Basin lies beyond in the "Rain Shadow." The Great Basin is sagebrush country. Small to medium size scrubs dominate in basins, pinyon and juniper woodlands take over as you ascend to medium elevations. Mountaintops often receive double or more the rainfall as do nearby basins, and reward the visitor with surprisingly rich ecosystems.

Sonoran Desert
This is considered by some to be the biologically richest desert in the world. It is a subtropical desert, receiving much of its moisture during the summer "Monsoon" season as tropical moisture is pulled deep in the desert. The winter rains that so influence the Great Basin are also felt here. The result is that the Sonoran has two distinct and often substantial rainy seasons, and ecosystems have responded to this relative bounty by becoming more complex.

Home to the stately Saguaro cactus, the northern part of this desert is in Arizona and California, but it pushes far down into Mexico on both sides of the Gulf of California. Much of the Sonoran is located in low elevation country, and its southerly location makes it a hot desert. Like all our deserts it is broken by numerous mountain ranges, which in Southwest are sometimes referred to as "Sky Islands" due to their isolation and biological diversity.

Mojave Desert
The Mojave is the smallest of the North American Deserts. It lies between the Sonoran and the Great Basin Deserts, and in some ways is transitional between the two. Many Great Basin species range south into the northern Mojave, and Sonoran species often exist in the southern Mojave. But the unique ecological requirements of this land have helped it create its own plants and animals, perhaps the most famous being the Joshua tree.

This area receive some of the summer "Monsoon" rains and some of the Pacific Northwest style rains in the winter, but its summer rainfall is nowhere near what it is in the Sonoran Desert and it winter precipitation falls far short of the Great Basin. In fact, this is the driest of the North American Deserts. Most areas receive less than six inches of annual rain, and in the deep heart of the Mojave in California rainfall is more like two to four inches a year. The former community of Bagdad, California once went an incredible 767 days without rain! The dry air also promotes higher temperatures. The all time record high for North America was recorded in Death Valley at 134 degrees.

Chihuahuan Desert
This desert lies primarily in Mexico, in the inter mountain basin in the Rocky Mountains between the Sierra Madre Oriental and the Sierra Madre Occidental. Most of this area is one of high elevations, with 3,000 to 6,000 feet being typical. A small northern portion extends into Arizona and New Mexico, but the majority is in the Mexican states of Chihuahua, Coahuila, Zacatecas and San Luis Potosi. Rainfall averages between eight and twelve inches, and is primarily a summer phenomenon. Agaves, commonly referred to as Century Plants, are one of the characteristic plants of this desert.