Hawaii (Listeni/həˈwaɪ(j)i/ hə-wy-(y)ee, or, locally, [həˈwɐɪʔi]; Hawaiian: Hawaiʻi [hɐˈvɐiʔi]) is the 50th and most recent U.S. state to join the United States, having joined the Union on August 21, 1959. It is the only U.S. state located in Oceania and the only one made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean.