Mo. Rev. Stat. § 226.560
The provisions contained herein relating to size, spacing and lighting in zoned and unzoned commercial and industrial areas shall apply only to signs erected subsequent to March 30, 1972.
(L. 1965 2d Ex. Sess. p. 900 § 7, A.L. 1972 S.B. 382)
Effective 3-30-72