The Chihuahuan Desert is a desert

Desert

A desert is a landscape or region that receives an extremely low amount of precipitation, less than enough to support growth of most plants. Most deserts have an average annual precipitation of less than...

, and an ecoregion

Ecoregion

An ecoregion , sometimes called a bioregion, is an ecologically and geographically defined area that is smaller than an ecozone and larger than an ecosystem. Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural...

 designation, that straddles the U.S.-Mexico border in the central and northern portions of the Mexican Plateau

Mexican Plateau

The Central Mexican Plateau, also known as the Mexican Altiplano or Altiplanicie Mexicana, is a large arid-to-semiarid plateau that occupies much of northern and central Mexico...

, bordered on the west by the extensive Sierra Madre Occidental

Sierra Madre Occidental

The Sierra Madre Occidental is a mountain range in western Mexico.-Setting:The range runs north to south, from just south of the Sonora–Arizona border southeast through eastern Sonora, western Chihuahua, Sinaloa, Durango, Zacatecas, Nayarit, Jalisco, Aguascalientes to Guanajuato, where it joins...

 range, and overlaying northern portions of the east range, the Sierra Madre Oriental

Sierra Madre Oriental

The Sierra Madre Oriental is a mountain range in northeastern Mexico.-Setting:Spanning the Sierra Madre Oriental runs from Coahuila south through Nuevo León, southwest Tamaulipas, San Luis Potosí, Querétaro, and Hidalgo to northern Puebla, where it joins with the east-west running Eje Volcánico...

. On the U.S.

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 side it occupies the valleys and basins of central and southern New Mexico

New Mexico

New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...

, Texas

Texas

Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...

 west of the Pecos River

Pecos River

The headwaters of the Pecos River are located north of Pecos, New Mexico, United States, at an elevation of over 12,000 feet on the western slope of the Sangre de Cristo mountain range in Mora County. The river flows for through the eastern portion of that state and neighboring Texas before it...

 and southeastern Arizona

Arizona

Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...

; south of the border, it covers the northern half of the Mexican

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 state of Chihuahua, most of Coahuila

Coahuila

Coahuila, formally Coahuila de Zaragoza , officially Estado Libre y Soberano de Coahuila de Zaragoza is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico...

, north-east portion of Durango

Durango

Durango officially Estado Libre y Soberano de Durango is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. The state is located in Northwest Mexico. With a population of 1,632,934, it has Mexico's second-lowest population density, after Baja...

, extreme northern portion of Zacatecas

Zacatecas

Zacatecas officially Estado Libre y Soberano de Zacatecas is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 58 municipalities and its capital city is Zacatecas....

 and small western portions of Nuevo León

Nuevo León

Nuevo León It is located in Northeastern Mexico. It is bordered by the states of Tamaulipas to the north and east, San Luis Potosí to the south, and Coahuila to the west. To the north, Nuevo León has a 15 kilometer stretch of the U.S.-Mexico border adjacent to the U.S...

.