Tex. Government Code § 433.003: DURATION OF STATE OF EMERGENCY.

(a) Except as provided by Subsection (b), a directive expires 72 hours after the time of proclamation of the state of emergency for which it was issued.

(b) The governor by proclamation may terminate or set a shorter period for a directive. The governor may proclaim successive states of emergency, each not exceeding 72 hours, as necessary to protect health, life, and property in the affected area, and may extend a directive from one state of emergency to the next.

Acts 1987, 70th Leg., ch. 147, Sec. 1, eff. Sept. 1, 1987.