1. The Battle of Pilot Knob: On October 6th, 1864, the Battle of Pilot Knob, also known as the Battle of Fort Davidson, took place in Iron County, Missouri during the American Civil War. Confederate forces, led by General Sterling Price, attacked Union troops in an attempt to capture St. Louis. However, Union forces were able to successfully defend their position and thwart the Confederate advance.

2. Missouri's First State Fair: The first Missouri State Fair was held in St. Louis on October 6, 1852. The fair was designed to promote agriculture and encourage Missouri farmers to improve their practices. It included exhibits of livestock, produce, and agricultural machinery, as well as entertainment and educational programs.

3. Jesse James: On October 6th, 1866, infamous outlaw Jesse James robbed his first bank in Liberty, Missouri. Along with his gang, James was able to steal nearly $60,000 from the Clay County Savings Association. This marked the beginning of a series of robberies that would make James one of the most notorious figures of the Old West.

4. Truman Elected to Senate: On October 6th, 1934, Harry S. Truman was elected to the United States Senate from Missouri. Truman would go on to become Vice President under Franklin D. Roosevelt and later President of the United States following Roosevelt's death. Truman's election to the Senate was a significant moment in Missouri and American political history.

5. Gateway Arch Construction: On October 6th, 1963, construction began on the Gateway Arch in St. Louis, Missouri. The arch, designed by Finnish-American architect Eero Saarinen, stands 630 feet tall and is the tallest arch in the world. Construction took just over two years to complete and the arch has since become a symbol of the city of St. Louis and the state of Missouri as a whole.