Mo. Rev. Stat. § 171.051
171.051 School holidays.
171.051. School holidays. — School holidays include Thanksgiving Day, December twenty-fifth, the third Monday in February, July fourth, and may include November eleventh at the discretion of the school district.
(L. 1963 p. 200 § 11-5, A.L. 1969 p. 85, A.L. 2014 S.B. 600) (Source: RSMo 1959 § 163.020)