1. On December 21, 1817, Mississippi became the 20th state in the United States. Jackson, the capital city, officially became the state capital in 1821.

2. In 1935, the new Mississippi State Capitol building was dedicated on December 21. It was constructed in the Art Deco style and designed by Theodore Link, who also designed the St. Louis Union Station.

3. On December 21, 1862, Confederate forces won a significant victory over Union forces at the Battle of Chickasaw Bayou, near Vicksburg. The Confederate victory helped prevent the Union Army from capturing Vicksburg for another six months.

4. In 1932, the famous blues musician Robert Johnson recorded several of his songs for the first time on December 21 at the Gunter Hotel in San Antonio, Texas. Johnson's music has had a major impact on blues and rock musicians for decades.

5. On December 21, 1970, the Mississippi River Bridge connecting Vicksburg, Mississippi, and Delta, Louisiana, opened to traffic. The bridge, which is over 3 miles long, was the longest river bridge in the United States at the time of its opening.