A modern seat belt indicator light.

Seat belts have been around for so long they sometimes don’t get their due when people consider important advances in car safety. In fact, they are one of the most effective pieces of safety equipment in your car. The National Highway Traffic Safety Administration estimates that seat belts have saved more than 300,000 lives since 1960 and 15,000 in 2016 (the most recent year for which data is available). That compares with about 2,700 for airbags in 2016. Seat belts have evolved over the past seven decades from a basic strap to today’s highly engineered mechanisms that do far more than most passengers realize.

These devices, on all driver and front passenger seats since 2008, have a mechanism that tightens the belt across a passenger’s waist and/or chest in a crash. Upon impact, sensors—much like those used in airbags—trigger mechanisms that clamp down and take up belt slack. The occupant is held in place to reduce the risk that the body will come into contact with something in a crash. Pretensioners also ensure that occupants are in the safest position during airbag deployment.

More on Car Safety

Inflatable Seat Belts
Ford introduced the inflatable seat belt in rear seats of the 2011 Explorer SUV. It’s a cross between a traditional seat belt and an airbag. In a crash, the belt inflates like a long, balloon-shaped airbag across the chest, increasing the contact surface area between the belt and the body more than five times. The bag remains inflated for several seconds. The technology may protect occupants better in certain crashes, such as rollovers.

Load Limiters
These are designed to reduce the potential for injury from a too-tight seat belt during a crash. The load limiter allows the seat belt to spool out a little bit at a time in a controlled way, reducing the force the belt applies to the passenger’s chest. Volvo introduced load limiters in 1995; their use is now widespread.

Seat Belt History Highlights


The first known patent for a vehicular seat belt is given to Edward J. Claghorn by the U.S. Patent Office.


Gustave-Désiré Leveau of France invents a seat belt system with adjustable diagonal chest and lap belts.


Members of the medical profession urge the automotive industry “to equip automobiles with seat belts as standard.”


Nash automobiles are the first to offer factory-installed lap belts.


Roger W. Griswold and Hugh DeHaven obtain a patent for a three-point belt.


Ford and Chrysler begin to offer lap belts.


Consumer Reports finds that many cross-lap seat belts fail basic safety and durability tests.


Volvos become the first cars to be fitted with three-point lap-and-shoulder belts.


Ralph Nader’s “Unsafe at Any Speed,” an indictment of the auto industry for its lack of safety standards, is published.


The new National Highway Safety Bureau (later to become NHTSA) requires passenger cars to have lap belts for each designated seat. Shoulder belts are required if crash tests prove they’re necessary.


The federal government requires shoulder belts in the outboard front seats of all passenger cars. At that time, shoulder belts could still be separate or integrated with lap belts. Also, NHTSA’s safety standard for a 30-mph frontal barrier crash test requires manual seat belts to remain intact.


Because of low use of the separate shoulder belts and lap belts, integrated three-point lap-and-shoulder belts are required in the outboard front seats of passenger cars.


Observed seat belt use is measured at 19 percent.


New York sets the first mandatory seat belt law. Within three years, 28 more states will follow.


Cars are required to have three-point lap-and-shoulder belts in the outboard rear seats.


The overall observed seat belt use rate reaches 58 percent.


All rear seats, including the middle one, are required to have three-point lap-and-shoulder belts in passenger cars and light trucks.


The observed seat belt use rate increases to 88.5 percent.

Editor’s Note: This article also appeared in the May 2019 issue of Consumer Reports magazine.