There are 7 US Post Offices in Island County serving a total of 62,845 residents equating to 8,978 residents per post office. It's estimated that approximately 100,308 packages are handled across the 7 county post offices annually. 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 is composed entirely of islands. It contains 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. Island County comprises the Oak Harbor, WA Micropolitan Statistical Area, which is also included in the Seattle-Tacoma, WA Combined Statistical Area."