1. On October 3, 1872, the Missouri Pacific Railroad opened its first line between St. Louis and Kansas City, marking a major milestone in the state's transportation history. The railroad helped spur economic growth and development in many parts of Missouri.

2. In 1910, the first Boy Scout troop in Missouri was organized in St. Louis on October 3. The Boy Scouts of America quickly became a popular organization in Missouri and across the country, promoting outdoor activities, community service, and character development for young men.

3. On October 3, 1927, the film "Upstream" premiered in St. Louis. Directed by the legendary silent film director John Ford, the movie was a critical success and helped establish St. Louis as a major center for film production during the early years of the film industry.

4. In 1934, the notorious gangster Pretty Boy Floyd was killed by FBI agents in East Liverpool, Ohio on October 3. Floyd had a long criminal career that included several high-profile bank robberies in Missouri and other states, and his death marked the end of an era of gang violence and lawlessness in the Midwest.

5. On October 3, 1967, the legendary rock band The Doors played a concert at the Municipal Auditorium in Kansas City, Missouri. The sold-out show was part of the band's first national tour and helped establish them as one of the most influential rock bands of the 1960s. Some fans even claimed that Jim Morrison, the band's charismatic frontman, was inspired to write the song "Waiting for the Sun" after seeing the sunrise over Kansas City on the morning of the show.