Mo. Const. art. III, § 42

No local or special law shall be passed unless a notice, setting forth the intention to apply therefor and the substance of the contemplated law, shall have been published in the locality where the matter or thing to be affected is situated at least thirty days prior to the introduction of the bill into the general assembly and in the manner provided by law. Proof of publication shall be filed with the general assembly before the act shall be passed and the notice shall be recited in the act. [Effective - 27 Feb 1945 , see footnote]