1. On May 9, 1868, the Great Mahele was officially enacted in Hawaii. This was a land redistribution act that aimed to modernize Hawaiian land ownership by establishing private ownership of land instead of communal ownership.

2. In 1901, on May 9th, the first electric trolley system was introduced in Honolulu. The trolley system would go on to play a major role in Honolulu's transportation until the 1950s when it was replaced by buses.

3. On May 9, 1929, a massive fire broke out in Honolulu's Chinatown. The fire destroyed over 38 acres of the city and left thousands homeless. It is recognized as one of Honolulu's worst disasters in history.

4. In 1960, on May 9th, the USS Swordfish, a submarine that was decommissioned after serving in World War II, was purposely sunk off the coast of Oahu to serve as a training site for future underwater demolitions teams.

5. On May 9, 1978, the first Hawaiian Ironman Triathlon was held on the island of Oahu. The race consisted of a 2.4-mile swim, 112-mile bike ride, and a 26.2-mile run. The race has since become a beloved annual event attracting athletes from around the world.