1. 1776: Delaware Declares Independence - On May 15, 1776, the Delaware Assembly unanimously passed a resolution declaring independence from Great Britain, making it the first state to do so. This resolution led to the drafting of Delaware's first constitution, which was adopted two months later.

2. 1888: Delaware Park Opens - On May 15, 1888, Delaware Park, a thoroughbred racetrack and casino, opened in Stanton, Delaware. It was one of the first racetracks in the country to offer parimutuel wagering, which is still used today.

3. 1941: Delaware Memorial Bridge Opens - On May 15, 1941, the Delaware Memorial Bridge, which spans the Delaware River and connects Delaware to New Jersey, officially opened to traffic. The bridge was named in honor of the soldiers and sailors from Delaware who lost their lives in World War I.

4. 1981: First African American Elected to Delaware State Senate - On May 15, 1981, Herman M. Holloway Sr. became the first African American to be elected to the Delaware State Senate. He served in the Senate until 1994 and was a champion for civil rights and social justice.

5. 1992: Ratification of the 27th Amendment - On May 15, 1992, Delaware became the 38th state to ratify the 27th Amendment to the U.S. Constitution, which prohibits Congress from giving itself a pay raise during a current session of Congress. This amendment was originally proposed in 1789 but was not ratified until over 200 years later.