| May 31, 1915|
| 89.840 mph (144.583 km/h)|For 1915, riding mechanics were required.
(Note 1) Louis Chevrolet is usually shown as American but his application for a US passport (available at ) reveals that he did not become a US citizen until June 1915.
(Note 2) Ralph DePalma is usually shown as American but his application for a US passport (available at ) reveals that he did not become a US citizen until 1920.
1915 Indianapolis 500 Wikipedia
The 5th International 500-Mile Sweepstakes Race was held at the Indianapolis Motor Speedway on Monday, May 31, 1915. The traditional race date of May 30 fell on a Sunday, but race organizers declined to schedule the race for Sunday. The race was set for Saturday May 29, but heavy rains in the days leading up to the race flooded the grounds and made some roads leading to the track impassible. Officials decided to postpone the race until Monday May 31 in order to allow the grounds to dry out. Speedway management would maintain their policy to not race on Sundays until 1974.
After a heartbreaking loss in 1912, Ralph DePalma succeeds in victory for 1915. DePalma was accompanied by riding mechanic Louis Fontaine.