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Events
- 1814 – The Treaty of Fort Jackson was signed, ending the Creek War and giving 23 million acres to the United States
- 1842 – Webster–Ashburton Treaty is signed, establishing the United States–Canada border east of the Rocky Mountains.
- 1862 – American Civil War: Battle of Cedar Mountain – At Cedar Mountain, Virginia, Confederate General Stonewall Jackson narrowly defeats Union forces under General John Pope.
- 1877 – Indian Wars: Battle of Big Hole – A small band of Nez Percé Indians clash with the United States Army.
- 1892 – Thomas Edison receives a patent for a two–way telegraph.
- 1936 – Summer Olympic Games: Games of the XI Olympiad: Jesse Owens wins his fourth gold medal at the games becoming the first American to win four medals in one Olympiad.
- 1944 – The United States Forest Service and the Wartime Advertising Council release posters featuring Smokey Bear for the first time.
- 1945 – World War II: Nagasaki is devastated when an atomic bomb, "Fat Man", is dropped by the United States B-29 Bockscar. 70,000 people are killed instantly.
- 1965 – A fire at a Titan missile base near Little Rock, Arkansas kills 53 construction workers.
- 1969 – Members of a cult led by Charles Manson brutally murder pregnant actress Sharon Tate (wife of Roman Polanski), coffee heiress Abigail Folger, Polish actor Wojciech Frykowski, men's hairstylist Jay Sebring, and recent high–school graduate Steven Parent at 10050 Cielo Drive in Los Angeles, California.
- 1974 – As a direct result of the Watergate scandal, Richard Nixon becomes the first President of the United States to resign from office. His Vice President, Gerald Ford, becomes president.
- 1988 – The first official night game is played at Chicago's Wrigley Field, the last Major League ballpark to install lights, some 40 years after the second–to–last team, the Detroit Tigers.
- 2001 – US President George W. Bush announces his support for federal funding of limited research on embryonic stem cells.