- The US Air Force insisted that the alien bodies that people saw near Roswell were dummies. (1997) In 1947, witnesses claimed to have seen an alien craft crash near Roswell, New Mexico. The government argued that it was wreckage from a surveillance balloon project called "Mogul." The controversy, and conspiracy theories, about what really crashed continue to this day.
- European explorer John Cabot became the first European to record seeing North America. (1497) Italian navigator Giovanni Caboto, called John Cabot by the English, likely saw what is now Canada during his exploration. Though this generally accepted, Canadian and British governments argue that he saw Newfoundland.
- Struck with a sudden illness, Germans in the streets of Aachen, Germany, hallucinated and started to jump, twist and writhe until they fell from exhaustion. (1374) It was one of the first known instances of St. John's Dance. Outbreaks were experienced by thousands of people through centuries. The illness may have been brought on by a poisonous fungus, but scientists have never reached a conclusive cause.
- The first widely witnessed UFO sighting was recorded. (1947) Kenneth Arnold made the report at Mount Rainier in Washington state. He claimed nine pie-plate-shaped objects were hovering in a chain near Mount Rainier. The U.S. Air Force declared the sighting to be a mirage.
- The world's longest suspension bridge opened. (1981) The Humber Bridge was the world's longest suspension bridge for its first 17 years. It is 4,626 feet (1,410 meters) long. It has since fallen to fifth place — Akashi Kaikyo Bridge in Japan is the longest suspension bridge in the world at 6,532 feet (1,991 meters) long.
- The song O Canada was first performed. (1880) It was performed at the Congres national des Canadiens-Francais and would become Canada's national anthem 100 years later in 1980 with the passing of the the National Anthem Act.
- Picasso held his first major exhibition. (1901) The exhibition opened on a street in Paris, rue Lafitte. Picasso was just 19 years old and completely unknown, but had already painted hundreds of works. He first exhibited his work when he was 13 years old and promptly quit art school so he could experiment on his own.
- U.S. President Grover Cleveland died. (1908) President Cleveland was the 22nd and 24th President of the United States — the only U.S. president elected to non-consecutive terms. He died at age 71 from a heart attack.
- New York state declared capital punishment unconstitutional. (2004) All death row inmates' sentences were commuted to life sentences, and "death row" was removed in 2008. The first U.S. state to ban the death penalty was Michigan in 1846.
- American boxer Jack Dempsey was born. (1895) From 1919 to 1926, Dempsey was the American world heavyweight boxing champion. In 83 fights, he had 66 wins — 51 of which were knockouts.
- American actor Jackie Gleason died. (1987) Perhaps best known for his role as Ralph Kramden on the American TV shoe The Honeymooners, Gleason also starred in several movies, including his role as Minnesota Fats in The Hustler, with Paul Newman. He was 71.
- Roy O. Disney was born. (1893) Disney was a co-founder of the Walt Disney company with his brother Walt.
- American author Ambrose Bierce was born. (1842) Bierce was perhaps best known for his satirical work The Devil's Dictionary. He disappeared in 1914 while traveling through Mexico and was never seen again.
