1. The first official state flag was adopted on December 18, 1924. The design features a traditional Osage Nation buffalo-skin shield with seven eagle feathers dangling from the lower edge of the shield, representing the seven clans of the Osage Nation.

2. On December 18, 1932, oil was discovered in the city of Tulsa. The discovery led to a boom in oil production and helped establish Tulsa as a major oil center in the United States.

3. December 18, 1907, marked the day that Oklahoma was admitted as the 46th state in the United States. President Theodore Roosevelt signed the proclamation that made Oklahoma a state.

4. On December 18, 1962, the first successful liver transplant was performed in the United States by Dr. Thomas Starzl at the University of Colorado. The patient, a 3-year-old girl from Oklahoma, survived for an additional six years.

5. The University of Oklahoma football team won its first national championship on December 18, 1950. The Sooners defeated the University of Tennessee in the Orange Bowl to complete an undefeated season and claim the title.