1. In 1898, Hawaii officially became a territory of the United States with the signing of the Hawaiian Organic Act on April 21st. This act established a government for Hawaii and paved the way for eventual statehood.

2. On April 21, 1949, the territory of Hawaii held its first general election since the end of World War II. Governor Ingram Stainback won re-election in a close race against Democratic challenger Philip L. Rice.

3. In 1978, the Hawaii State Legislature approved a landmark law protecting the environment and the rights of Native Hawaiians. Known as the State Water Code, the law established new regulations for water use and management in Hawaii.

4. On April 21, 1989, the iconic Aloha Stadium in Honolulu hosted its first NFL draft. The stadium, which opened in 1975, has been the home of many historic sporting events in Hawaii, including the Pro Bowl and NCAA college football games.

5. In 2018, Hawaii made history by becoming the first US state to ban the use of pesticides containing chlorpyrifos, a harmful chemical linked to developmental and neurological issues in children. The ban was signed into law on April 21st by Governor David Ige, marking a major victory for environmental advocates and public health advocates in Hawaii.