The aftermath of the worst tragedy in racing history. 

The worst crash in the history of motorsports occurred on this date 57 years ago during the 24 Hours of Le Mans. The accident claimed the life of the driver involved, Pierre Levegh, as well as 83 spectators, and changed forever the previously cavalier attitude toward safety in racing.

The 49-year-old Levegh arrived at Le Mans that year in an inspired frame of mind, having secured a factory drive for Mercedes-Benz largely through the notoriety of his performance in the 1952 race, when he had driven for 23 hours (!) to maintain his overall lead, but missed a gear change due to exhaustion with just 45 minutes remaining, and blew his car's engine. For the '55 race, Levegh was driving one of Mercedes' new 300 SLR sports cars, which featured a body made of a lightweight magnesium alloy.

At the end of the 35th lap, Levegh was following Mike Hawthorn's leading Jaguar D-type when Hawthorn belatedly noticed a pit signal to stop for fuel. Hawthorn slowed suddenly in an effort to stop, causing a chain-reaction in which Levegh's Mercedes somersaulted onto an earthen mound, shedding parts that went into the crowd, and then catching fire as its fuel tank ruptured, igniting the alloy bodywork. Rescue workers – unfamiliar with the chemical properties of magnesium – poured water on the fire, intensifying the blaze. The awful final reckoning included 83 spectators dead – along with Levegh, who had been ejected from his seatbelt-less car – and another 120 injured.

Despite the awful carnage, the race continued to its conclusion – officials claimed stopping it would have made things harder for emergency crews trying to get in and out of the track, although press coverage played up the seemingly callous aspect of the continuation.

An official inquiry into the accident ruled it a purely racing incident, although the deaths of the spectators were attributed to inadequate safety standards at the track, which had basically been unchanged since the first Le Mans race in 1923. The worldwide shock that resulted from the incident led to an outright ban on motorsports in France, Spain, Switzerland, Germany, and several other nations, while Mercedes withdrew from racing at the end of the year. Le Mans was obliged to demolish its main grandstand and pit areas before racing could resume there.

In the U.S., the American Automobile Association (AAA), which had been the primary sanctioning body for American motorsports, dissolved its Contest Board in response to the Le Mans disaster, prompting Indianapolis Motor Speedway owner Tony Hulman's decision to form the United States Auto Club (USAC).