Tex. Local Government Code § 263.202

(a) A county that owns land used for public purposes that exceeds the amount of land needed by the county for its public purposes may sell all or part of the excess to the United States at a private sale for any fair consideration approved by the commissioners court of the county. The sale must be made under the statutes of the United States authorizing the acquisition of sites for public buildings.

(b) The commissioners court of the county is responsible for determining whether an excess of land exists and the extent to which the excess may be sold and conveyed under this section.

(c) For a conveyance under this section to be effective, the commissioners court must authorize the conveyance by an order entered in its minutes. The order must:

(1) describe the land to be conveyed;

(2) state the consideration to be paid; and

(3) direct the county judge of the county to execute in the name of the county a conveyance to the United States and to promptly make delivery of the conveyance on payment of the consideration to the appropriate officer of the county.

(d) An instrument of conveyance executed by the county judge must be in the form, and contain the covenants and warranties, prescribed by the commissioners court. The instrument must reserve concurrent jurisdiction over the conveyed land for the service of all state criminal and civil process.