Hawaii was incorporated into the Union as its 50th state on August 21 1959, when President Dwight D. Eisenhower signed its statehood bill. It had been annexed by the United States much earlier, in July 1898, when a joint resolution of U.S. Congress decided to depose the Hawaiian Queen, Liliuokalani, without due process or fair compensation.
Prior to the signing of Hawaii's statehood bill, there was some deliberation over which territory to incorporate first: Alaska or Hawaii. Eisenhower wanted to incorporate Hawaii first, fearing that an Alaskan state government would pose a potential threat to executive control of defense installations in the region, which served as an important deterrent against Soviet Union advances.
Congress, however, was hungry for the economic benefits of Alaskan oil, and pressurized the president to make Alaska the 49th state. An influential racist element within Congress also had deep reservations about extending full statehood status to the largely non-white population of Hawaii.
Eventually, President Eisenhower accepted the will of Congress and Alaska became the 49th state in 1959. This was under the proviso that defense installations in the territory would remain under federal control and could be increased in number without state government interference. Hawaii followed after racially motivated opposition was outvoted.