Tex. Transportation Code § 364.045

(a) A county may issue combination tax and revenue bonds to construct all or part of an international toll bridge or other improvement spanning the Rio Grande and may impose an ad valorem tax to pay all or part of the bonds if the issuance of the bonds and the imposition of the tax are approved by a majority of the votes received at an election held in the county for that purpose.

(b) The commissioners court of a county may call an election under this section on its own motion at any regular session of the court. The commissioners court shall call an election under this section at the next regular session of the court following the submission to the court of a petition requesting the election signed by a number of registered voters of the county that is equal to at least one percent of the number of votes cast in the county in the most recent general election for governor.

(c) The election order and notice of election must include:

(1) the purpose for which the bonds are to be issued;

(2) the amount of the bonds;

(3) the rate of interest; and

(4) a statement that unlimited ad valorem taxes are to be imposed annually on all taxable property in the county in amounts sufficient, together with revenues from the county toll bridge or toll bridge system, to pay the bonds at maturity.

(d) The bonds must be made payable from revenues of the county toll bridge or toll bridge system and from ad valorem taxes imposed and collected in accordance with Section 52, Article III, Texas Constitution. The ad valorem taxes must be imposed in amounts that, together with revenues from the county toll bridge or toll bridge system, are sufficient to retire the bonds.

(e) The county may execute an agreement, contract, or trust with a private entity or with the United Mexican States or a political subdivision, department, or agency of the United Mexican States to finance, construct, operate, or maintain an international toll bridge in its entirety or other improvement spanning the Rio Grande.