| Kentucky Derby | |
| Location | Churchill Downs |
|---|---|
| Date | May 21, 1878 |
| Winning horse | Day Star |
| Jockey | Jimmy Carter |
| Surface | Dirt |
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The 1878 Kentucky Derby was the 4th running of the Kentucky Derby. The race took place on May 21, 1878. Winning horse Day Star set a new Kentucky Derby record with a winning time of 2:37.25.