1. Delaware becomes the first state to ratify the U.S. Constitution. On December 31, 1787, Delaware became the first state to ratify the U.S. Constitution, which established the framework for the federal government still in use today.

2. Wilmington experiences one of its deadliest fires. On December 31, 1909, a massive fire broke out in Wilmington that would go on to claim the lives of 12 firefighters and four civilians, making it one of the deadliest fires in the city's history.

3. Delaware State University is officially established. On December 31, 1891, Delaware State University (then known as the State College for Colored Students) was officially established by an act of the Delaware General Assembly. Today, it is one of two historically black colleges and universities in the state.

4. Wilmington native Thomas Garrett helps Harriet Tubman with Underground Railroad efforts. On December 31, 1849, Wilmington native Thomas Garrett provided critical assistance to abolitionist Harriet Tubman as she helped a group of enslaved individuals escape to freedom via the Underground Railroad.

5. Delaware's first official flag is adopted. On December 31, 1913, Delaware's first official state flag was adopted, featuring a colonial blue background with a diamond shape in the center and the state's coat of arms in the middle. The flag is still in use today.