1. Delaware became the first state to ratify the United States Constitution on December 9, 1787. This historical event is celebrated every year in the state as "Delaware Day".

2. On December 9, 1803, the Delaware General Assembly met in Dover to approve the purchase of a statehouse in the city. This building still stands today and is known as the Old State House.

3. Renowned physician and Delaware native Dr. James Tilton was born on December 9, 1745. He served as the Surgeon General of the United States Army during the American Revolution and later as a member of Congress.

4. On December 9, 1913, the Delaware State Hospital for the Insane (now known as the Delaware Psychiatric Center) officially opened in New Castle County. It was the first state-funded mental health institution in Delaware.

5. The Dover International Speedway held its first NASCAR Cup Series race on December 9, 1969. The race was won by Richard Petty and the speedway continues to host major motorsports events to this day.