[3] It occurs in south-central regions of the US and northeastern Mexico, as well as several isolated introduced records and populations from Southern United States.

[9] The Texas horned lizard, like all members of the genus Phrynosoma, is endemic to North America where it occurs in south-central regions of the US and northeastern Mexico.

In Mexico it occurs in extreme eastern Sonora, most of Chihuahua, northeast Durango, northern Zacatecas and San Luis Potosí, and throughout most of Coahuila, Nuevo León, and Tamaulipas.

Ecological associations include the southern Great Plains, Edwards Plateau, Tamaulipan mezquital, Chihuahua Desert, Llanos el Salado, and many peripheral and marginal areas of these ecoregions.

The eastern distributional limit of the Texas horned lizard in the piney woods region of east Texas and western Louisiana, and the Ozark Mountain forests of western Arkansas, and Missouri likely represent introductions however, some have argued these records reflect natural relic populations.

[10] Many records of introductions from areas beyond its natural range have been reported as a result of released and escaped individuals from the pet trade in the early and mid-twentieth century, including: Alabama, Arizona, Colorado, the District of Columbia, Illinois, Indiana, Kentucky, Michigan, Mississippi, Nebraska, North Carolina, Tennessee, Virginia, and Wyoming, although these do not represent established, breeding populations.

The Texas horned lizard, along with at least three other species of the genus Phrynosoma, also has the ability to squirt an aimed stream of blood from the corners of the eyes and sometimes from its mouth at a distance up to 5 ft (1.5 m).

[citation needed] The decline is usually blamed on overuse of pesticides and the spread of nonnative, highly aggressive and fiercely territorial red imported fire ants.

A University of Texas publication notes that horned lizard populations continue to disappear throughout the southwest despite protective legislation.

The Center said it may later seek protection for the animal on a Federal level; it also said that reptiles in general are dying off at up to 10,000 times their historic extinction rate, greatly due to human influences.

Hatchlings are bred and released in targeted areas in the hope that with a large number of animals, enough will survive to grow the population in the wild.

[30] The project's goals are aimed at shedding light on the life history, population density, and determining ecological conditions best suited for this threatened species.