Mo. Rev. Stat. § 52.361

It shall be the duty of the county collector in all counties of the first class not having a charter form of government and in class two counties to prepare and keep in the collector's office, electronically or otherwise, back tax books which shall contain and list all delinquent taxes on real and personal property levied and assessed in the county which remain due and unpaid after the first day of January of each year. Such back tax books shall replace and be in lieu of all "delinquent lists" and other back tax books heretofore prepared by the collector or other county officer.