|Indianapolis Motor Speedway|
|Date||May 30, 1921|
|Winning Entrant||Louis Chevrolet|
|Average speed||89.621 mph (144.231 km/h)|
|Pole position||Ralph DePalma|
|Pole speed||100.750 mph (162.141 km/h)|
|Most laps led||Ralph DePalma (108)|
|Pace car||H.C.S. 6|
|Pace car driver||Harry C. Stutz|
|Starter||Thomas J. Hay|
|Honorary referee||David Beecroft|
|Estimated attendance||135,000-150,000 ("last year was 125k")|
The 9th International 500-Mile Sweepstakes Race was held at the Indianapolis Motor Speedway on Monday, May 30, 1921.
Ralph DePalma dominated another early running of the 500, but again failed to win. He led 109 laps, and had a two-lap lead at the halfway point. A connecting rod broke, and he dropped out on lap 112. DePalma retired with one win, and 612 laps led in the "500." His laps led record would not be matched for 66 years until Al Unser, Sr. reached it in 1987.
Tommy Milton won the first of two 500 victories. He was accompanied by riding mechanic Harry Franck. The only European car to finish was a 1921 Grand Prix Sunbeam driven by Ora Haibe who was placed fifth.
Time trials was scheduled for five days, May 25–29. Four-lap (10 mile) qualifying runs were utilized. A short field of only 26 cars submitted entries, but only 23 cars arrived and prepared to qualify. Mervin Headley's entry was disallowed because only half the entry fee was paid. Two other entries were no-shows.
Ralph De Palma completed his qualifying run on Wednesday May 25, at an average speed of 100.75 mph. He won the pole position as the only driver over the 100 mph mark. None of his four laps matched the track record (104.78 mph) set in 1919.
This would be the first 500 that featured the familiar starting grid of rows of cars three-abreast.
|1||20||2||Tommy Milton||Louis Chevrolet||Frontenac||Frontenac||93.050||11||200||90||5:34:44.65|
|2||2||6||Roscoe Sarles||Duesenberg Brothers||Duesenberg||Duesenberg||98.350||2||200||1||5:38:34.03|
|3||8||23||Percy Ford||Stanley Kandul||Frontenac||Frontenac||87.000||19||200||0||5:52:15.30|
|4||9||5||Eddie Miller||Duesenberg Brothers||Duesenberg||Duesenberg||83.850||20||200||0||5:54:24.98|
|5||13||16||Ora Haibe||Sunbeam Motor Car Company||Sunbeam||Sunbeam||93.500||10||200||0||5:57:45.83|
|6||14||9||Albert Guyot||Duesenberg Brothers||Duesenberg||Duesenberg||87.800||16||200||0||6:01:17.07|
|7||10||3||Ira Vail||Ira Vail||Leach||Miller||82.350||22||200||0||6:14:17.47|
|8||15||21||Bennett Hill||John Thiele||Duesenberg||Duesenberg||87.780||17||200||0||6:19:06.74|
|9||21||8||Ralph Mulford||Louis Chevrolet||Frontenac||Frontenac||91.700||12||177||0||Flagged|
|10||17||15||René Thomas||Sunbeam Motor Car Company||Sunbeam||Sunbeam||83.750||21||144||0||Water hose|
|11||18||27||Tom Alley||L. L. Corum||Frontenac||Frontenac||80.500||23||133||0||Rod|
|12||1||4||Ralph DePalma||Ralph DePalma||Ballot||Ballot||100.750||1||112||108||Rod|
|13||4||1||Eddie Hearne||E. A. Hearne||Duesenberg||Duesenberg||96.180||6||111||0||Oil line|
|14||19||24||Jimmy Murphy||Duesenberg Brothers||Duesenberg||Duesenberg||93.600||9||107||0||Crash T4|
|15||16||17||Riley Brett||George L. Wade||Brett||Brett||87.750||18||91||0||Hit wall|
|16||23||28||C. W. Van Ranst||C. W. Van Ranst||Frontenac||Frontenac||88.350||14||87||0||Water hose|
|17||3||7||Joe Boyer||Duesenberg Brothers||Duesenberg||Duesenberg||96.650||4||74||1||Rear axle|
|18||6||19||Jean Chassagne||Jean Chassagne||Peugeot||Peugeot||91.000||13||65||0||Lost hood|
|19||5||22||Jules Ellingboe||Jules Ellingboe||Frontenac||Frontenac||95.400||8||49||0||Steering|
|20||11||14||André Boillot||Louis Coatalen||Sunbeam||Sunbeam||97.600||3||41||0||Rod bearing|
|21||7||18||Louis Fontaine||George L. Wade||Brett||Brett||88.300||15||33||0||Crash FS|
|22||22||25||Joe Thomas||Duesenberg Brothers||Duesenberg||Duesenberg||96.250||5||25||0||Crash T3|
|23||12||10||Howdy Wilcox||Jules Goux||Peugeot||Peugeot||96.000||7||22||0||Rod|
- Fox, Jack C. (1994). The Illustrated History of the Indianapolis 500 1911-1994 (4th ed.). Carl Hungness Publishing. p. 22. ISBN 0-915088-05-3.
- "Race Throngs Upset Records". The Indianapolis Star. May 31, 1921. p. 1. Retrieved June 3, 2017 – via Newspapers.com.
- The Talk of Gasoline Alley - 1070-AM WIBC, May 5, 2004
- Local Indy 500 links from long ago
- "Indianapolis 500 1921". Ultimate Racing History. Archived from the original on 3 March 2016. Retrieved 15 January 2012.
- Ikert, B. M. (1921-06-02). Motor Age: American Cars Dominate 500-Mile Race. Class Journal Company. p. 1.
- Popely, Rick; Riggs, L. Spencer (1998). The Indianapolis 500 Chronicle. Lincolnwood, Illinois: Publications International, Ltd. ISBN 0-7853-2798-3.
- Blazier, John E.; Rollings, Tom (1994). Forgotten Heroes of the Speedways: The Riding Mechanics.
- The Talk of Gasoline Alley - 1070-AM WIBC, May 14, 2004