1. On December 20, 1915, the Missouri State Capitol was formally dedicated in Jefferson City. The Capitol building had been under construction since 1913, and its completion marked a major milestone in Missouri politics and government.

2. December 20, 1861, saw the Battle of Blackwater Creek, which took place near Warrensburg, Missouri. Union forces under the command of General James A. Mulligan defeated a Confederate raiding party, securing a vital supply line for Union forces.

3. In 1803, on December 20, Missouri was part of the Louisiana Purchase, when the United States acquired Louisiana from France for $15 million. This event helped to double the size of the United States, opening up new lands for settlement and exploration.

4. On December 20, 1834, the steamboat Thomas Swann exploded on the Mississippi River near New Madrid, Missouri, killing over 100 people. The disaster was one of many similar steamboat accidents to occur on the river during the 19th century.

5. December 20, 1944, marks the date of the Battle of the Bulge, one of the largest and deadliest battles of World War II. Missouri soldiers played a vital role in the conflict, helping to turn the tide in favor of the Allied forces and bringing an end to the Nazi advance.