Mo. Rev. Stat. § 226.573
The state highways and transportation commission is authorized to adopt administrative rules regulating the use of new technology in outdoor advertising as allowed under federal regulations for federal-aid primary highways as of June 1, 1991, and all highways designated as part of the National Highway System by the National Highway System Designation Act of 1995 and those highways subsequently designated as part of the National Highway System. Any rule or portion of a rule, as that term is defined in section 536.010, that is promulgated pursuant to the authority delegated in this section shall become effective only if it has been promulgated pursuant to the provisions of chapter 536. This section and chapter 536 are nonseverable and if any of the powers vested with the general assembly pursuant to chapter 536 to review, to delay the effective date or to disapprove and annul a rule are subsequently held unconstitutional, then the grant of rulemaking authority and any rule proposed or adopted after August 28, 2002, shall be invalid and void.
§ 226.573, RSMo