David "Salt" Walther was a driver in the USAC and CART Championship Car series. He also drove NASCAR stock cars and unlimited hydroplane boats, and was a car owner in USAC. Walther is best remembered for a crash at the start of the 1973 Indianapolis 500 that left him critically injured. He recovered from his injuries, returned in 1974, and placed 9th in the 1976 race. He also co-drove a car with Bob Harkey to 10th place in 1975.

The 57th 500 Mile International Sweepstakes was held at the Indianapolis Motor Speedway in Speedway, Indiana, on Wednesday, May 30, 1973. The race was held over three days due to rain and suffered two major accidents. Three competitors - two drivers and one pit crew member - died from injuries suffered as a result of accidents that occurred during the month, another driver was critically injured, and over a dozen spectators suffered injuries and/or burns. After 133 laps, rain halted the race, and Gordon Johncock was declared the winner, the first of his two Indy triumphs.