1. On September 20, 1845, the Kingdom of Hawaii officially established its first postal service. The service was initially limited to the island of Oahu, but quickly expanded to include other islands.

2. In 1946, the Waikiki Theatre, which was one of the largest and most popular movie theaters in Honolulu, opened its doors for the first time on September 20. The theater operated for over 70 years before closing in 2018.

3. On September 20, 1999, Hurricane Iniki struck the island of Kauai, causing significant damage and widespread power outages. The category 4 hurricane was one of the most powerful storms to hit Hawaii in modern history.

4. In 2001, the Hawaii State Capitol building in Honolulu was officially dedicated on September 20. The modernist structure was designed by architect John Carl Warnecke and features a distinctive cone-shaped roof.

5. On September 20, 2014, the Polynesian Voyaging Society's traditional voyaging canoe, the Hokulea, departed from Hilo on the Big Island of Hawaii on a historic around-the-world journey. The voyage, which was aimed at promoting cultural and environmental awareness, lasted over three years and covered over 40,000 nautical miles.