Mo. Rev. Stat. § 301.707: Registration required, exceptions.

1. No person shall operate an all-terrain vehicle within the state unless the all-terrain vehicle has been registered with the department of revenue.

2. A registration is not required for the following:

(1) All-terrain vehicles owned and operated by the United States, another state, or a political subdivision thereof;

(2) All-terrain vehicles owned and operated by this state or by any municipality or political subdivision thereof;

(3) All-terrain vehicles covered by a valid registration of another state or country that have not been within this state for more than thirty days.

3. No person under sixteen years of age shall be allowed to register an all-terrain vehicle.