1. On March 15, 1820, Missouri became a state in the United States of America. This came after a long process of becoming a territory and finalizing the Missouri Compromise, which allowed for Missouri's admission to the Union as a slave state while also prohibiting slavery north of the 36°30' latitude line.

2. On March 15, 1861, Missouri's government officially declared its neutrality in the Civil War. This decision was made despite the state's divided loyalties and the fact that both the Union and Confederate armies were active within its borders.

3. On March 15, 1937, a massive tornado struck the city of St. Louis, Missouri, killing 72 people and causing extensive damage. The storm was part of a larger outbreak of tornadoes that struck the Midwest that day, with more than 500 people losing their lives in the disaster.

4. On March 15, 1957, the Mark Twain Boyhood Home and Museum opened in Hannibal, Missouri. Located in the house where the famous author spent his formative years, the museum has since become a popular tourist destination and cultural landmark.

5. On March 15, 2007, Missouri became the first state in the country to adopt a statewide texting while driving ban. The law prohibits drivers of all ages from sending or reading text messages while behind the wheel, with violators subject to fines and other penalties. Since then, many other states have followed suit in enacting similar laws.