Tex. Loc. Gov't Code § 352.003
(a) For use in protecting bridges, county shops, county warehouses, and other property located outside the municipalities in a county with a population of 350,001 to 449,999, the commissioners court of the county may:
(b) In a county with a population of less than 20,000 and a property valuation of more than $100 million according to the most recently approved county tax rolls, the commissioners court of the county may:
Acts 1987, 70th Leg., ch. 149, Sec. 1, eff. Sept. 1, 1987.