Tex. Loc. Gov't Code § 327.051

The commissioners court of a county with a population of more than 2.1 million that is adjacent to a county with a population of more than 2.1 million by order may authorize the creation of a zoo board under this chapter to establish, finance, and manage facilities and services to provide conservation, education, research, public recreation, and care relating to the study and display of animals and other specimens in a public zoological park.