1. On February 20, 1783, peace negotiations between the United States and Great Britain began in Paris, France. Delaware had played a significant role in the Revolutionary War, with many residents serving in the Continental Army, and the peace negotiations signaled the end of the war and the beginning of a new era for the state and the country.

2. February 20, 1865, marked the day that the 12th Amendment to the United States Constitution was ratified by Delaware. The amendment established a new procedure for electing the president and vice president and is considered an important milestone in American political history.

3. On February 20, 1929, the DuPont Company introduced their synthetic rubber called neoprene. This breakthrough product was used for a wide variety of applications, including wetsuits, seals, and medical equipment. Neoprene became one of the company's most successful products and helped to establish Delaware as a leader in the chemical industry.

4. February 20, 1959, was the day that Delaware officially adopted the state's official flag. The design features a buff-colored diamond on a field of colonial blue, with the state coat of arms in the center.

5. On February 20, 1982, the Delaware General Assembly voted to make the horseshoe crab the state marine animal. The horseshoe crab, which has been around for over 450 million years, is an important part of Delaware's ecosystem and plays a crucial role in the medical industry, where its blood is used to detect bacterial contamination in vaccines and medical equipment.