Statehood Day or Admission Day is a legal holiday in the state of Hawaii in the United States. It is celebrated annually on the third Friday in August to commemorate the anniversary of the 1959 admission of Hawaii into the Union. It was first celebrated in 1969. 
Statehood bills for Hawaii were introduced into the U.S. Congress as early as 1919 by Prince Jonah Kuhio Kalanianaole, the non-voting delegate sent by the Territory of Hawaii to the U.S. Congress. Additional bills were introduced in 1935, 1947 and 1950. In 1959, the U.S. Congress approved the statehood bill, the Hawaii Admission Act. This was followed by a referendum in which Hawaiian residents voted 94% in support of statehood (the ballot question was: "Shall Hawaii immediately be admitted into the Union as a state?"), and on August 21, 1959 (the third Friday in August), President Dwight D. Eisenhower signed a proclamation making Hawaii the 50th state.
(federal) = federal holidays, (state) = state holidays, (religious) = religious holidays, (week) = weeklong holidays, (month) = monthlong holidays, (36) = Title 36 Observances and Ceremonies Bolded text indicates major holidays that are commonly celebrated by Americans, which often represent the major celebrations of the month.