Wikipedia:Selected anniversaries/April 3
- 1860 - The first successful Pony Express run was started.
- 1948 - The Marshall Plan to financially assist the re-building of Europe following World War II began.
- 1974 - The Super Outbreak of 148 tornadoes killed 315 people and injured 5,484 in 13 U.S. states at the end of a very strong La Niña event.
- 1975 - Bobby Fischer refused to play Anatoly Karpov, giving Karpov the chess title.
- 1996 - Suspected "Unabomber" Theodore Kaczynski was arrested.