Mo. Rev. Stat. § 57.115: Sheriff may patrol roads and highways (third and fourth class counties).

Sheriffs in counties of the third and fourth class may:

(1) Regularly patrol and police all public roads and highways within the county;

(2) Enforce all laws designed to safeguard and protect these roads and highways;

(3) Report all dangerous conditions on these roads and highways to the county commission or other road or highway supervising body.