1. Missouri's Constitution Day: On September 16, 1820, Missouri was officially recognized as a state in the United States, and its constitution was adopted. This day is now known as Constitution Day in Missouri.

2. Missouri State Fair: The annual Missouri State Fair always takes place during the second week of August, but it actually starts on September 16 with the Governor's Ham Breakfast. This event has been a tradition since 1951 and is attended by thousands of people each year.

3. Route 66: On September 16, 1926, the iconic Route 66 highway was officially created by the US government. A section of this famous road runs through Missouri, and it has become an important part of the state's history and culture.

4. Harry Truman: September 16 is the birthday of Missouri's most famous and influential politician, Harry S. Truman. Truman served as the 33rd President of the United States, and his home state of Missouri has honored him in many ways, including by naming the state fairgrounds after him.

5. Civil War History: On September 16, 1861, one of the first battles of the Civil War took place in Missouri. The Battle of Dry Wood Creek was fought near the town of Fort Scott, and it ended in a Confederate victory. This was just the beginning of Missouri's involvement in the long and bloody conflict.