There are 12 US Post Offices in Chelan County serving a total of 72,375 residents equating to 6,031 residents per post office. It's estimated that approximately 115,519 packages are handled across the 12 county post offices annually. Chelan County /\u0283\u0259\u02c8l\u00e6n/ is a county in the U.S. state of Washington. As of the 2010 census, its population was 72,453. The county seat and largest city is Wenatchee. The county was created out of Okanogan and Kittitas Counties on March 13, 1899. It derives its name from a Chelan Indian word meaning \"deep water,\" likely a reference to 55-mile (89 km)-long Lake Chelan, which reaches a maximum depth of 1,486 feet (453 m). Chelan County is part of the Wenatchee, Washington, Metropolitan Statistical Area."