The 31st International 500-Mile Sweepstakes was held at Indianapolis Motor Speedway on Friday, May 30, 1947. The 1946 winner, George Robson, had been killed in the meantime.

Late in the race, Lou Moore teammates Bill Holland and Mauri Rose were running 1st and 2nd. The pit crew displayed a confusing chalkboard sign with the letters "EZY" to Holland, presumably meaning for him to take the final laps at a reduced pace to safely make it to the finish. Mauri Rose ignored the board, and charged to catch up to Holland. Holland believed he held a lap lead over Rose, and allowed him to catch up. The two drivers waved as Rose passed Holland, with Holland believing it was not more than a congratulatory gesture.

In reality, the pass Rose made was for the lead, and he led the final 8 laps to take the controversial victory. The race was marred by a 41st lap crash that claimed the life of Shorty Cantlon.

Time trials was scheduled for five days. The minimum speed to qualify was set at 115 mph. In the months leading up to the race, several top drivers that were members of a union, the American Society of Professional Auto Racing (ASPAR), threatened to boycott the race over the purse size. The AAA Contest Board refused to heed their demands, and when the entry list was closed on May 8, many of the top drivers, particularly several popular west coast drivers, were not on the list. A total of 35 cars were entered, but at least nine had no driver listed, and 13 of the entries were inexperienced novice drivers. After the practice began for the month, officials decreed that the boycotting drivers would not be allowed late entry. After several weeks of dispute, an agreement was made for the ASPAR drivers to participate mid-way through the month.

When qualifying closed at 6 p.m. on Wednesday May 28, the field had only been filled to 28 cars.Duke Dinsmore was the final qualifier, completing his run amidst some scoring confusion by the officials, just as the time had run out. Race officials initially stressed that Wednesday would be the final day available to qualify. However, a day later, they re-opened qualifying for one hour late on Thursday May 29 in an effort to fill the field. Mel Hansen and Emil Andres were the only two cars to complete attempts, and after approval by the other entries, were added to the grid to bring the field to 30 cars.

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Wikipedia