Tex. Education Code § 66.24: AUTHORIZED INVESTMENTS; SECURITY FOR DEPOSITS.

All bonds and notes, whether original or refunding, issued pursuant to the constitutional provisions or issued pursuant to this subchapter, shall be fully negotiable instruments, and all bonds and notes are declared to be legal and authorized investments for banks, savings banks, trust companies, building and loan associations, savings and loan associations, insurance companies, fiduciaries, trustees, guardians, and for the sinking funds of cities, towns, villages, counties, school districts, and all other political corporations or subdivisions of the State of Texas; and the bonds and notes shall be eligible to secure the deposit of any and all public funds of the State of Texas, and any and all public funds of cities, towns, villages, counties, school districts, and all other political corporations or subdivisions of the State of Texas; and the bonds and notes shall be lawful and sufficient security for those deposits to the extent of their par value when accompanied by all unmatured coupons appurtenant to them.

Acts 1971, 62nd Leg., p. 3150, ch. 1024, art. 1, Sec. 1, eff. Sept. 1, 1971.