1. Missouri became a state on August 10, 1821, but it wasn't until August 20 of that same year that the first session of the Missouri General Assembly was held.
2. On August 20, 1862, the Battle of Lone Jack took place in Jackson County, Missouri during the American Civil War. The Confederate victory led to the burning of the town of Lone Jack.
3. The American Royal, a livestock show and horse show held annually in Kansas City, Missouri, was founded on August 20, 1899.
4. On August 20, 1936, baseball legend Ty Cobb played in his last game as a member of the Detroit Tigers at Sportsman's Park in St. Louis, Missouri. Cobb went 0-for-4 and retired with a career batting average of .366, the highest in Major League Baseball history.
5. August 20, 1986 marked the launch of the Challenger Space Shuttle mission STS-51-F, which carried out experiments in astronomy and astrophysics. The mission was notable for the onboard participation of Saudi Arabian astronaut Sultan bin Salman Al Saud, who became the first Arab, Muslim, and royal to fly into space.