Prince Kūhiō Day is an official holiday in the state of Hawaiʻi in the United States. It is celebrated annually on March 26, to mark the birth of Prince Jonah Kūhiō Kalanianaʻole — heir to the throne of the Kingdom of Hawaiʻi, prince of the House of Kalākaua, and later territorial delegate to the United States Congress. It is one of only two holidays in the United States dedicated to royalty, the other being Hawaiʻi's King Kamehameha Day June 11.