1. On September 20, 1777, the Battle of Brandywine was fought near Chadds Ford, Pennsylvania, just across the Delaware border. The British victory allowed them to march to Philadelphia unopposed, leading to the occupation of the city for much of the Revolutionary War.

2. In 1865, on September 20, the Delaware State Fair Association was founded. To this day, the Delaware State Fair remains an annual event showcasing agriculture, entertainment, and local culture.

3. The Wilmington High School for Girls, now known as Wilmington Friends School, was founded on September 20, 1888. It was the first all-girls secondary school in Delaware and remains a prestigious institution to this day.

4. On September 20, 1948, the first commercial airline flight arrived at the Wilmington-New Castle Airport. The airport now serves as a hub for major airlines and is an important transportation center in the region.

5. September 20, 1991, saw the establishment of the Nemours Health and Prevention Services division. Nemours is a nonprofit pediatric health system that provides medical care, research, and advocacy on behalf of children and families.