1. In 1820, Missouri was admitted as the 24th state in the Union, following the Missouri Compromise which settled a dispute over whether it would enter the Union as a slave state or a free state.

2. In 1977, the Ozark National Scenic Riverways was established in southeastern Missouri, becoming the first national park area dedicated to the protection of a river system.

3. On September 25, 1917, Fort Leonard Wood was established in central Missouri as a training center for soldiers during World War I. It continues to serve as a major military installation for the U.S. Army today.

4. The Gateway Arch, a monument symbolizing westward expansion and the city of St. Louis, was completed on September 25, 1965 after years of planning and construction. The arch stands 630 feet tall and is the tallest man-made monument in the United States.

5. In 1998, Missouri voters approved a law banning indoor smoking in most public places, making it one of the first states to do so. The law went into effect in 1999 and has since been expanded to include bars and casinos.