- Dr. Martin Luther King, Jr. was assassinated. (1968) King's death rocked the nation and was immediately surrounded by conspiracy theories, despite the fact that James Earl Ray admitted to the crime. King is still considered one of the most influential figures of the 20th century.
- Ben-Hur won 11 Academy Awards. (1960) Only two other films have tied Ben-Hur's record for Oscar wins: Titanic and The Lord of the Rings: The Return of the King.
- The US started using the Stars and Stripes flag. (1818) There had been several other American flag designs adopted before the modern Stars and Stripes, including one for which the designer asked to be paid "a quarter cask of the public wine."
- William Henry Harrison succumbed to pneumonia. (1841) Harrison was the first president to die in office and also the president to serve the shortest term in office — one month. He died after contracting pneumonia while giving his inauguration speech, which was the longest in presidential history.
- The song "Dixie" got its debut. (1859) The song, which later became associated with the antebellum South, actually originated out of a blackface show in New York. The show was wildly popular throughout the Civil War, and remains a symbol of the idealized antebellum South.
- The Kennel Club was founded. (1873) The Kennel Club was the first official registry for purebred dogs in the world, and recognizes only about 200 breeds of dog.
- The peace sign was first displayed. (1958) The Campaign for Nuclear Disarmament (CND) peace sign is often considered to be the symbol of the 1960s antiwar and free love culture, and is one of the most internationally recognized symbols in the world.
- Microsoft was founded. (1975) The company was originally a small partnership between Bill Gates and Paul Allen after they read about a new microcomputer in Popular Science and realized they could implement Gates' BASIC language with it. The company produced its first operating system five years later.
- The NATO Treaty was signed. (1949) The treaty was originally signed to contain Soviet aggression, and played a large role in European politics throughout the Cold War, especially in the civil war in Bosnia.
- Britain got its first Prime Minister. (1721) Robert Walpole came into office on the tail end of the South Sea Bubble collapse and was credited with leading the country out of financial disaster, cementing the importance of the Prime Minister position in British government.