|- location||Guadalupe Peak|
|- elevation||2,667 m (8,750 ft)|
|- location||Pecos - Rio Grande Confluence|
|- elevation||300 m (984 ft)|
|Area||31,479 sq mi (81,530 km2)|
|Density||26 / sq mi (10 / km2)|
|Website: Handbook of Texas: Trans-Pecos|
The term Trans-Pecos, as originally defined in 1887 by the Texas geologist Robert T. Hill, refers to the portion of Texas that lies west of the Pecos River. The term is considered synonymous with "Far West Texas", a subdivision of West Texas. The Trans-Pecos lies within the Chihuahuan Desert, the most mountainous and arid portion of the state, and it is well known for its scenic desert vistas, such as Big Bend National Park and the Guadalupe Mountains.
The Trans-Pecos region is divided into nine large counties: Brewster, Culberson, El Paso, Hudspeth, Jeff Davis, Pecos, Presidio, Reeves, and Terrell counties (See table below). Brewster County, the largest, has a land area of 6,193 sq mi (16,040 km2). To put this figure in perspective, consider that the land area of Brewster County is approximately 10% larger than the entire state of Connecticut, yet it has a population density of only 1.4 persons per square mile compared to the 723 persons per square mile that reside in Connecticut. However, Brewster County is not the least populated of the nine counties that comprise the Trans-Pecos. Terrell County, which borders both the Pecos River and the Rio Grande, is the least populated county in the Trans-Pecos region. According to the United States Census of 2000, Terrell County had a total population of 1,081 residents occupying a land area of 2,358 sq mi (6,107 km2) resulting in a population density of less than 0.5 persons per square mile.
The Trans-Pecos is a region of extremes, and at the opposite extreme from sparsely populated Terrell County is El Paso County, which is the smallest but most populated of the nine counties. El Paso County has a land area of only 1,015 sq mi (2,629 km2), yet it has a population of 775,085 individuals, resulting in a population density of 764 persons per square mile, a value that exceeds the 723 persons per square mile population density of Connecticut.
Overall, the total population of the Trans-Pecos amounts to 830,808 residents occupying an area of 31,479 sq mi (81,530 km2) resulting in a population density of around 26 persons per square mile (10 persons per km2).
|County||Area (mi2)||Population||Pop. Density
See also 
- List of geographical regions in Texas
- Chalk Mountains
- Davis Mountains
- Guadalupe Mountains
- McKittrick Canyon
- Big Bend
- Hill, R.T. 1887. The topography and geology of the Cross Timbers and surrounding regions in Northern Texas. The American Journal of Science, 3rd Series, 33:291-303.
- Greene, A.C. 1998. Sketches from the five states of Texas. College Station: Texas A&M University Press, 176 pp.
- Hammond's Complete World Atlas. New York: C.S. Hammond and Company, 1951.
- Trans-Pecos Geology Resources Walter Geology Library, The University of Texas at Austin
- Photos of West Texas