Except for New Hampshire, all states and the District of Columbia require adult front-seat occupants of motor vehicles to use seat belts. Adult rear-seat passengers are also covered by the laws in 31 states and the District of Columbia. Children are covered by separate laws.

State seat belt laws are divided into two categories: primary and secondary. Primary seat belt laws allow law enforcement officers to stop a motor vehicle and to issue a ticket or citation to a driver or passenger for not wearing a seat belt without any other traffic offense having occurred. Secondary seat belt laws only allow law enforcement officers to issue a ticket or citation for not wearing a seat belt when there has been another traffic offense by an occupant of the vehicle for which the occupant may be issued a ticket or citation.

In Missouri (MO), the state enforces primary seat belt laws for drivers and front-seat passengers, meaning law enforcement officers can stop and ticket drivers solely for not wearing a seat belt. Missouri law requires all drivers and front-seat passengers to wear seat belts. Additionally, children under 16 years old must wear seat belts or be in an appropriate child safety seat, regardless of their seating position in the vehicle. For rear-seat passengers who are 16 years of age or older, the seat belt law is secondary, which means they can only be ticketed for not wearing a seat belt if the vehicle is stopped for another traffic violation. It's important to note that child passenger restraint laws are more stringent and require specific types of safety seats depending on a child's age, height, and weight.