Events
- 1673 – Louis Joliet and Jacques Marquette begin exploring the Mississippi River.
- 1775 – American Revolutionary War: The Continental Congress bans trade with Canada.
- 1792 – The New York Stock Exchange is formed.
- 1849 – A fire threatens to burn St. Louis, Missouri, to the ground.
- 1875 – Aristides wins the first Kentucky Derby.
- 1927 – U.S. Army aviation pioneer, Major Harold Geiger, died in the crash of his Airco DH.4 de Havilland plane at Olmstead Field, Pennsylvania.
- 1943 – The United States Army contracts with the University of Pennsylvania's Moore School to develop the ENIAC.
- 1954 – The United States Supreme Court hands down a unanimous decision in Brown v. Board of Education of Topeka, Kansas.
- 1963 – Bruno Sammartino defeats Nature Boy Buddy Rogers in 48 seconds in Madison Square Garden for the WWWF Heavyweight Championship. It begins the longest heavyweight championship reign in pro wrestling history.
- 1973 – Watergate scandal: Hearings begin in the United States Senate and are televised.
- 1974 – Police in Los Angeles, California, raid the Symbionese Liberation Army's headquarters, killing six members, including Camilla Hall.
- 1983 – Lebanon, Israel, and the United States sign an agreement on Israeli withdrawal from Lebanon.
- 1987 – An Iraqi fighter jet fires two missiles into the U.S. warship USS Stark (FFG-31), killing 37 and injuring 21 of her crew.
- 2004 – Massachusetts becomes the first U.S. state to legalize same-sex marriage.
- 2006 – The aircraft carrier USS Oriskany sunk in the Gulf of Mexico to be an artificial reef.