1. On May 9, 1927, the DuPont Company announced plans to build a new experimental laboratory in Wilmington, Delaware. The laboratory would be dedicated to developing new materials and technologies for DuPont's various businesses.

2. In 1932, on May 9, Delaware became the first state in the U.S. to adopt a Workers' Compensation law. The law provided injured workers with medical treatment and financial compensation for lost wages due to a work-related injury or illness.

3. On May 9, 1960, the first laser was demonstrated in Wilmington, Delaware by scientists at the DuPont Company's Experimental Station. The laser, which used a ruby crystal as the emitting medium, was an important milestone in the development of laser technology.

4. In 1988, on May 9, the Delaware Museum of Natural History opened its doors to the public. The museum, located in Wilmington, features exhibits on the natural history of Delaware and the surrounding region, including fossils, minerals, and live animals.

5. On May 9, 2002, Delaware Senator Joe Biden announced his candidacy for president of the United States. Although Biden's campaign ultimately ended without securing the Democratic nomination, he would go on to serve as vice president under Barack Obama and later become the 46th president of the United States in 2021.