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.

New Hampshire is unique among U.S. states as it does not require adult front-seat occupants to wear seat belts. However, the state does have mandatory seat belt laws for minors. New Hampshire's seat belt laws for children require that all children under the age of 18 must be properly restrained in a vehicle. For adults, wearing a seat belt is a matter of personal choice and there are no penalties for not wearing one. It's important to note that while New Hampshire does not have a primary or secondary seat belt law for adults, it does enforce child restraint laws vigorously. These laws are in place to ensure the safety of young passengers, and failure to comply can result in fines and penalties.