Mo. Rev. Stat. § 307.085: Cowl, fender, running board and backup lamps — violation, penalty.

1. Any motor vehicle may be equipped with not more than two side cowl or fender lamps which shall emit a white or yellow light without glare. Any motor vehicle may be equipped with not more than one running board courtesy lamp on each side thereof which shall emit a white or yellow light without glare. Any motor vehicle may be equipped with a backup lamp either separately or in combination with another lamp; except that no such backup lamp shall be continuously lighted when the motor vehicle is in forward motion.

2. Notwithstanding the provisions of section 307.120, violation of this section is an infraction.