Andrei Sakharov 1921 - Soviet physicist, he came to be regarded as the father of the Soviet hydrogen bomb, Soviet antiwar activist
- 1542 - Hernando de Soto died along the Mississippi River while searching for gold.
- 1819 - Bicycles were first seen in the U.S. in New York City. They were originally known as "swift walkers."
- 1881 - The American branch of the Red Cross was founded by Clara Barton.
- 1924 - Fourteen-year-old Bobby Franks was murdered in a "thrill killing" committed by Nathan Leopold Jr. and Richard Loeb. The killers were students at the University of Chicago.
- 1927 - Charles A. Lindberg completed the first solo nonstop airplane flight across the Atlantic Ocean. The trip began May 20.
- 1968 - The nuclear-powered U.S. submarine Scorpion, with 99 men aboard, was last heard from. The remains of the sub were later found on the ocean floor 400 miles southwest of the Azores.