The Chihuahuan Desert (, ) is a desert ecoregion designation covering parts of northern Mexico and the southwestern United States. It occupies much of far West Texas, the middle to lower Rio Grande Valley and the lower Pecos Valley in New Mexico, and a portion of southeastern Arizona, as well as the central and northern portions of the Mexican Plateau. It is bordered on the west by the Sonoran Desert, the Colorado Plateau, and the extensive Sierra Madre Occidental range, along with the northwestern lowlands of the Sierra Madre Oriental range. Its largest, continual expanse is located in Mexico, covering a large portion of the state of Chihuahua, along with portions of Coahuila, north-eastern Durango, the extreme northern part of Zacatecas, and small western portions of Nuevo León. With an area of about , The desert is fairly young, existing for only 8,000 years. Many native grasses and other species have become dominated by woody native plants, including creosote bush and mesquite, due to overgrazing and other urbanization. The Mexican wolf, once abundant, was nearly extinct and remains on the endangered species list.
Climate
The desert is mainly a rain shadow desert because the two main mountain ranges which bound the desert, the Sierra Madre Occidental to the west and the Sierra Madre Oriental to the east, block most moisture from the Pacific Ocean and the Gulf of Mexico, respectively. Climatically, the desert mostly has an arid, mesothermal climate with one rainy season in the late summer and smaller amounts of precipitation in early winter, the mean daily temperature of the coldest month warmer than .
Owing to its inland position and higher elevation than the Sonoran Desert to the west, mostly varying from in elevation, the desert has a slightly milder climate in the summer (though usually daytime June temperatures are in the range of ), with mild to cool winters and occasional to frequent freezes. Snowfall is scant except at the higher elevation edges. Northern and eastern portions have more definite winters than southern and western portions, receiving a portion of winter precipitation as snowfall most winters.
Protected areas
A 2017 assessment found that , or 7%, of the ecoregion is in protected areas.