1. On March 20, 1820, Missouri was officially admitted as the 24th state in the United States. This followed a controversial period in which tensions mounted between pro-slavery and anti-slavery advocates.

2. March 20, 1865, saw the fall of Petersburg, Virginia in the American Civil War. This event paved the way for the eventual surrender of Confederate General Robert E. Lee and the end of the war.

3. In March 20, 1912, Woodrow Wilson became the first presidential candidate to campaign in Missouri by automobile. He had previously campaigned on horseback and via train.

4. The first recorded use of the phrase "Show-Me State" to describe Missouri occurred on March 20, 1899, in an address by Congressman Willard Vandiver. He stated: "I come from a state that raises corn and cotton, and cockleburs and Democrats, and frothy eloquence neither convinces nor satisfies me. I am from Missouri. You have got to show me." This phrase has since become a popular nickname for the state.

5. On March 20, 1933, Missouri Governor Guy B. Park signed a bill authorizing the construction of the Mark Twain Dam on the Salt River. The dam, which was completed in 1952, helps regulate water levels and prevent flooding in the area.