1. Derby was incorporated as a town on May 15, 1775. Originally a farming community, it became known for its factories in the 19th and early 20th centuries.

2. On May 15, 1780, the British raided Fairfield, Connecticut during the Revolutionary War. They burned over 90 houses, including the town meeting house and church. The attack led to a wave of patriotism and support for the American cause.

3. The New Haven Railroad completed its Air Line route on May 15, 1873. The route was a shorter, more direct link from New York to Boston, and included the construction of a tunnel through the Berkshires.

4. Yale University held its first commencement ceremony on May 15, 1702. The institution, which was then known as the Collegiate School, had only one graduate that year: Jacob Hemingway.

5. Mystic Seaport, a museum and maritime history center in Mystic, Connecticut, opened to the public on May 15, 1930. The center features historic ships, interactive exhibits, and recreated 19th-century coastal village.