1. On June 20, 1782, the Continental Congress adopted the Great Seal of the United States, which includes the national emblem of the bald eagle and the Latin motto E pluribus unum ("out of many, one"). This event is significant to Delaware because the state was one of the original 13 colonies that formed the United States and played an important role in the adoption of the Great Seal.

2. In 1905, the first automobile race was held on the beach in Rehoboth, Delaware, on June 20. The race was part of a larger event called the "Rehoboth Beach Auto Carnival," which featured races, parades, and other activities. The event was attended by thousands of people and helped establish Rehoboth as a popular tourist destination.

3. Delaware became the first state to ratify the U.S. Constitution on June 20, 1787. This historic event took place at the Golden Fleece Tavern in Dover, Delaware, and paved the way for the formation of the United States government.

4. On June 20, 2003, the DuPont Environmental Education Center opened in Wilmington, Delaware. The center is a partnership between the City of Wilmington and the Delaware Nature Society and provides hands-on environmental education programs for visitors of all ages.

5. The iconic Delaware Memorial Bridge, which spans the Delaware River and connects Delaware and New Jersey, opened to traffic on June 20, 1951. The bridge is an important transportation link between the Northeastern United States and serves as a symbol of the state's economic progress and infrastructure.