Mo. Rev. Stat. § 257.260
Concessions to be reappraised each twenty years.
257.260. Concessions to be reappraised each twenty years. — Assignments, leases or permissions by the board of trustees for periods of greater than twenty years, shall have the rates therefor reappraised or redetermined by the board every twenty years.
(L. 1959 S.B. 199 § 26)