Texas Parks and Wildlife Code - PARKS & WILD § 31.071. Rearview Mirrors

(a) A vessel used to tow a person or persons on water skis or an aquaplane or similar device on the water of this state must have a rearview mirror of a size no less than four inches from bottom to top and across from one side to the other. The mirror must be mounted firmly so as to give the boat operator a full and complete view beyond the rear of the boat at all times.

(b) Subsection (a) of this section does not apply to vessels used in water ski tournaments, competitions, or exhibitions, or to a vessel that, in addition to its operator, has on board a person 13 years of age or older observing the progress of the person being towed.