Interesting Facts about Seat Belts
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Seat belts were first invented by George Cayley in the 1800s. Seat belts were introduced in aircraft in the 1930s. The automotive seat belt was introduced into the United States by Kenneth Ligon and his brother, Bob Ligon, whose patented quick release seat belt, the AutoCrat Safety Belt, was the first seat belt installed as original equipment in the US by Ford in its 1956 model year. The first seatbelt to be included as standard was on the 1959 Volvo. However, they were not required by law in the US on passenger vehicles until the 1968 model year.

Three point harnesses were first made readily available in mass-produced vehicles by Volvo. It was Swedish engineer Nils Bohlin who patented the modern three-point belt design and gave it to Volvo.

Three-point harnesses are similar to the lap and sash seat belts, but with one single continuous length of webbing. Three-point seat belts help spread out the energy of the moving body in a collision over the chest, pelvis, and shoulders. Until the 1970's three-point belts were commonly available only in the front seats of cars, the back seats having only lap belts. Evidence of the potential for lap belts to cause separation of the lumbar vertebrae and the sometimes associated paralysis, or "seat belt syndrome", has led to a revision of safety regulations in nearly all of the developed world requiring that all seats in a vehicle be equipped with three-point seat belts.

Most seat belts are equipped with locking mechanisms that tighten the belt when pulled hard (e.g. by the force of a passenger's body during a crash) but do not tighten when pulled slowly. Many are also equipped with 'pretensioners', which preemptively tighten the belt to prevent the passenger from jerking forward in a crash.