Ralph Nader’s full-throttle polemic against the auto industry, Unsafe at Any Speed, neatly distilled the problems faced by car drivers in the post-war era. While Nader placed the blame fully on automakers, saying they sacrificed safety at the altar of comfort and cosmetics, the National Highway Safety Bureau (predecessor agency the National Highway Traffic Safety Administration) thought the problem was at least as much environmental: unsafe roads and spotty enforcement were as much responsible as the poor designs. To help alleviate both problem, President Lyndon Johnson passed two acts, focusing on motor vehicle and road safety measures.

On this day, September 9, in 1966, shortly after passage of the Highway Safety Act, Congress passed and President Lyndon Johnson signed the National Traffic & Motor Vehicle Safety Act, mandating standard safety features for vehicles.

The Act for the first time required cars to have seatbelts for every passenger, self-sealing fuel tanks, shatter-resistant windshields and impact-absorbing wheels. The complementary Highway Safety Act put better road markers and signs, guardrails and center dividers keeping cars from straying into oncoming traffic. Together the two acts drastically improved the casualty rate from car collisions.