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 Montana (MT), the state enforces a secondary seat belt law for adult front-seat occupants, meaning that law enforcement officers can issue a citation for not wearing a seat belt only if the driver has been pulled over for another traffic violation. However, Montana has a primary seat belt law for drivers and passengers under the age of 18, which allows officers to stop and cite drivers or passengers solely for not wearing a seat belt. For children, Montana has specific child restraint laws that require appropriate car seats and booster seats for younger and smaller children. These laws are designed to ensure the safety of children when traveling in a motor vehicle and are more stringent than those for adult seat belt use.