- 312 Roman Emperor Constantine the Great is said to have received his famous Vision of the Cross
- 1795 Pinckney's Treaty [Treaty of San Lorenzo] signed by Spain and US, establishing the southern boundary of the US and giving Americans right to navigate the Mississippi River
- 1962 Black Saturday - Russian nuclear missile crisis in Cuba
- 1982 China announces its population at 1 billion people plus
- 1986 British government deregulates financial markets in a "Big Bang", enhancing London's status as a financial captial
DuPont announces its new synthetic polyamide fiber will be called "nylon"
On This Day in 1938