According to the National Highway Traffic Safety Administration, passengers are unrestrained in more than one half of all fatal car crashes. For a passenger riding in the backseat of a car at the time of a crash, wearing a seat belt is 44% more effective at preventing death than riding unrestrained. For those riding in the rear of vans and sport-utility vehicles (SUVs) during a crash, seat belts are 73% better at preventing fatalities.

In a crash, unbuckled back seat occupants become "back seat bullets". They continue to move at the same rate of speed as the vehicle they're in until they hit something - seat back, dashboard, windshield or people in the front seat.

Adult rear-seat passengers are covered by seat belt laws in only 28 states and the District of Columbia