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Oahu is the third-largest and most populated island of the Hawaiian Islands and of the U.S. state of Hawaii. The state capital, Honolulu, is on Oahu's southeast coast. The island of Oahu and the uninhabited Northwestern Hawaiian Islands constitute the City and County of Honolulu. In 2021, Oahu had a population of 995,638, up from 953,207 in 2010.