North America is home to expansive arid regions defined by low annual precipitation, typically less than 10 inches, and sparse vegetation cover. These conditions have created some of the continent’s most vast and unique ecosystems. This article explores the three largest deserts in North America by total contiguous area.
Defining North American Deserts
The deserts of North America span a significant portion of the continent, extending from the western United States deep into Mexico. These diverse environments are categorized by their thermal characteristics, broadly split into “hot” deserts, like the Sonoran and Chihuahuan, and “cold” deserts, such as the Great Basin. This classification dictates the type of specialized flora and fauna found in each region. Based on total continuous surface area, the three largest deserts are the Great Basin, the Chihuahuan, and the Sonoran.
The Great Basin: North America’s Largest Desert
The Great Basin Desert is the largest arid region on the continent, encompassing approximately 190,000 to 200,000 square miles across most of Nevada and parts of Utah, Oregon, and California. It is defined as a cold desert, where much of its annual precipitation (seven to twelve inches) falls as snow during the winter months. The desert lies in a classic rain shadow, situated between the Sierra Nevada mountains to the west and the Rocky Mountains to the east, which blocks most moisture from reaching the interior.
Its high-altitude location (4,000 to 6,500 feet) contributes to cold winters and a low, homogeneous vegetation community. The landscape is dominated by hardy shrubs like big sagebrush (Artemisia tridentata) and saltbush, which are adapted to the high salt content found in the soil. Specialized fauna, such as the kangaroo rat, rely on metabolic water produced from the breakdown of dry seeds. This high-elevation expanse is a collection of hundreds of parallel mountain ranges separated by broad, arid valleys, known as the basin-and-range system.
The Chihuahuan Desert: The Second Largest
The Chihuahuan Desert, the second largest in North America, spans approximately 140,000 to 200,000 square miles, extending from the southwestern United States into the Central Mexican Highlands. It covers large portions of the state of Chihuahua and other northern Mexican states before extending into Texas and New Mexico. Classified as a high-altitude desert (1,500 to 6,000 feet), it features a slightly milder summer climate but experiences mild to cool winters with occasional freezes.
The desert is isolated from other arid regions by the Sierra Madre Occidental and Oriental mountain ranges, which contributes to its exceptional biodiversity. This isolation has fostered an ecosystem rich in endemic species, boasting more than 400 species of cactus. The Chihuahuan Desert receives moisture from summer monsoon thunderstorms, supporting vast grasslands and unique geological features like the gypsum dunes of White Sands National Park.
The Sonoran Desert: The Third Largest
The Sonoran Desert is the third largest, covering about 100,000 to 120,000 square miles across parts of Arizona, California, and the Mexican states of Baja California and Sonora. It is distinct from the other two largest deserts due to its subtropical climate and the presence of two distinct rainy seasons (bimodal precipitation). The Sonoran receives lighter, widespread winter rainfall from Pacific frontal storms and heavy, localized summer thunderstorms from the monsoon season.
This reliable, biseasonal moisture results in the highest biological productivity and diversity of all North American deserts. The iconic Saguaro cactus (Carnegiea gigantea) is found only here and symbolizes the region. The Saguaro’s dependence on warm temperatures and bimodal rainfall prevents it from surviving in the colder Great Basin or the higher Chihuahuan Desert. The environment also supports dense stands of leguminous trees like palo verde and ironwood, contributing to the desert’s lush appearance compared to its arid neighbors.