Indianapolis is synonymous with racing, and on May 29 the 500-mile race at Indy will celebrate a century of speed and innovation.
It's the 100th anniversary, but the 95th race; the event was suspended during World Wars I and II.
For the auto industry, Indy is much more than four left turns at 200 mph.
The innovation started early: One hundred years ago, Ray Harroun entered the only single-seat car in the field, an Indianapolis-built Marmon Wasp, and won the first Indy 500 with a 3-by-8-inch mirror mounted on the car's hood. The mirror was a response to safety complaints voiced by competitors, all of whom rode with a passenger who kept a lookout for possible collisions.
According to Popular Mechanics, Harroun got the idea from a mirror he saw on a horse-drawn vehicle. And the rearview mirror was born.
That's one of the many ways Indy has sparked change in the auto industry, from marketing campaigns to supplier innovations to safety technology.
"Those techniques used in labs and in testing these cars helped accelerate what we do in developing cars to sell," Chevrolet spokesman David Caldwell said.
What follows is a look at 100 years of innovation and industry-changing moments.