Mo. Rev. Stat. § 64.645: Plan or regulations not to be changed without notice and hearing (second and third class counties).

After the adoption of a zoning plan or regulations adopted pursuant thereto, no use of any parcel of land included in the plan or regulations shall be changed without a public hearing and the person or body which conducts the hearing shall give notice, at least fifteen days before the hearing, by certified mail to all owners of any real property located within one thousand feet of the parcel of land for which the change is proposed.