The Indy 500 is a Memorial Day Weekend tradition that, save for six years during the two World Wars, has occurred annually since 1911, two years after Indianapolis Motor Speedway opened.
The 200-lap race around the four-turn, 2.5-mile (4.023-kilometer) Speedway, Indiana oval, known as the "Greatest Spectacle in Racing", is not the only event held at the track known as the "Brickyard". In fact, NASCAR's race at the venue is quite literally called the Brickyard 400.
But the Indy 500 is by far the venue's biggest event, and it is, in fact, the largest single-day sporting event in the world.
For the first time since the race's 100th running, the historic venue at the "Racing Capital of the World" is sold out for the race's 109th running in 2025. It marks the first sellout since Penske Entertainment Group purchased the track from Hulman & Company after the 2019 IndyCar season.
How many fans can attend the Indy 500?
As is the case when it comes to motorsports, exact attendance figures are not recorded for the Indy 500, but the 2016 race was said to have been watched by nearly 400,000 in-person spectators.
The permanent seating capacity at the venue, which features two 1/8-mile short chutes, four 1/4-mile turns, and two 5/8-mile straightaways, is listed at 257,325, making the track the highest capacity venue for any sporting event in the world, and by quite a wide margin.
With the 2025 sellout, the attendance is expected to exceed 350,000, given the fact that infield seating, including the Snake Pit, is included in that tally.
That number would put Indianapolis Motor Speedway at No. 55 when it comes to the most populated cities in the entire United States. The population of Indianapolis, Indiana is only 870,000 itself, making the track itself the state's second most populated "city" on race day.
It's something that any IndyCar fan, or really any sports fan, should try to be a part of at least once.
By comparison, the largest football stadium in the United States is Michigan Stadium, home of the Michigan Wolverines, in Ann Arbor, Michigan. The venue seats 107,601 and has hosted a record crowd of 115,109.
Maybe comparison isn't even the right word to use, because when it comes to the Indy 500, there really is no true comparison.