Island County is a county located in the U.S. state of Washington. As of the 2010 census, its population was 78,506. Its county seat is Coupeville, while its largest city is Oak Harbor.
Its name reflects the fact that it consists of two large islands, Whidbey and Camano, and seven smaller islands (Baby, Ben Ure, Deception, Kalamut, Minor, Smith, and Strawberry). Island County was created out of Thurston County on December 22, 1852, by the legislature of Oregon Territory, and is the eighth-oldest county in Washington. It originally encompassed what are now Snohomish, Skagit, Whatcom, and San Juan Counties.