Every mandatory safety system has had an effect on crash death/injury numbers. Seatbelts in the mid-’60s and later the 3 point belt (over the shoulder) did a great job at keeping people from flying around. Later advances like airbags, crumple zones, side-impact beams, better brakes and tires, breakaway inside RV mirrors, etc all save lives. Currently, we have over twice the cars on the roads driving close to 3 times the miles per year as the early ’60s and we have about half the traffic deaths. Buckle up.