Mo. Rev. Stat. § 230.020
Within sixty days after the taking effect of this chapter, it shall be the duty of the county commission in all counties of this state, except as otherwise in this chapter provided, to appoint four members of the county highway commission, one for a term of one year; one for a term of two years; one for a term of three years; and one for a term of four years. Upon expiration of the term of each of said county highway commissioners his successor shall be appointed for a term of four years, and every such county highway commissioner shall hold office for the term appointed and thereafter until his successor is appointed and qualified. Not more than two of said county highway commissioners shall be appointed from the same county commission district, and not more than two thereof shall be affiliated with the same political party. No person shall be eligible to appointment as a member of the county highway commission who shall not have attained the age of twenty-five years, and who at time of his appointment is not a bona fide resident of county wherein appointed, and possessed of a knowledge of the interest of said county, and a known supporter and advocate of a system of county highways, constructed and maintained with a view to affording the greatest convenience to the greatest number of inhabitants of the county in the matter of farm-to-market roads. Within ten days after their appointment the members of such county highway commission shall meet at the county seats and organize by the election of one of their number as president, and another as secretary, of said commission.
§ 230.020, RSMo