Missouri Revised Statutes Title IX. Suffrage and Elections § 115.353. Declarations of candidacy, where filed

(1) For presidential elector, United States senator, representative in Congress, statewide office, circuit judge not subject to the provisions of Article V, Section 25 of the Missouri Constitution, state senator and state representative, in the office of the secretary of state;

(2) For all county offices which for the purpose of election procedures shall include associate circuit judges not subject to the provisions of Article V, Section 25 of the Missouri Constitution, in the office of the county election authority;

(3) For all county offices, in the office of the county election authority. In any county in which there are two boards of election commissioners, the county clerk shall be deemed to be the election authority for purposes of this section.