Mo. Rev. Stat. § 536.027: Written comments to be retained as public record for three years.

Any written comment filed pursuant to section 536.021 in support of or opposition to a notice of proposed rulemaking and any written record of a public hearing in connection with a notice of proposed rulemaking shall be retained for a period of at least three years by the agency issuing the notice, and all such comments and other records shall be available for public inspection at all reasonable times.