Mo. Rev. Stat. § 307.065: New vehicles shall have beam indicator — violation, penalty.

1. Every new motor vehicle registered in this state after January 1, 1942, which has multiple-beam road lighting equipment shall be equipped with a beam indicator, which shall be lighted whenever the uppermost distribution of lights from the headlamps is in use, and shall not otherwise be lighted. Said indicator shall be so designed and located that when lighted it will be readily visible without glare to the driver of the vehicle so equipped.

2. Notwithstanding the provisions of section 307.120, violation of this section shall be deemed an infraction.