Only one of the four passengers in the car carrying Diana survived the crash. He was the bodyguard, Trevor Rees-Jones, who was wearing a seat belt.
In the months following the princess' death, seat-belt safety campaigns were launched in Europe, encouraging more back-seat riders to buckle up. In the U.S., two-thirds of drivers and passengers buckle up in the front seat, while only 34 percent wear seat belts when they sit in the back.
While 49 states have seat-belt laws, most cover the driver and front-seat passengers. Only 12 states have seat-belt laws that require back-seat occupants to buckle up. So, where the law doesn't apply, people in the back seat have no fear of getting a ticket for not wearing a seat belt.
CBS 'This Morning' asked a few Americans whether Princess Diana's death affected their seat-belt use.
"I figure if you're going to get in an accident, you're going to get hurt either way," one person said. "A seat belt might make a difference, might not. I prefer not to put it on."
Many people believe they are safer in the back seat, and experts agree. However, back-seat riders are still at risk. In 1996, 1,400 people who had not buckled up died in the back seat.
Back-seat pasengers are also at high risk of serious injury. An unbelted person in the back seat can become like an unguided missile during a crash, thrown around the car with amazing force.
Experts refer to this as "the elephant-in-the-back-seat syndrome" because, in a 55-mph crash, an average-sized person unbelted in the rear seat can fly forward at the force of 3,000 pounds. They cause serious damage, not only to themselves, but potentially to others in the car.
Parents should be especially careful to buckle up their children in the back. Research shows that properly restrained children in the back seat have the lowest crash death rates. So even if there is a front seat available, it's a good idea put all children ages 12 and under in the back seats, and make sure they're buckled up.
The bottom line is: Buckle up, whatever seat you're in.
Reported by Dr. Emily Senay