There are 18 US Post Offices in Okanogan County serving a total of 41,589 residents equating to 2,311 residents per post office. It's estimated that approximately 66,381 packages are handled across the 18 county post offices annually. Okanogan County /\u02cco\u028ak\u0259\u02c8n\u0252\u0261\u0259n/ is a county located in the U.S. state of Washington along the Canada\u2013US border. As of the 2010 census, the population was 41,120. The county seat is Okanogan, while the largest city is Omak. In area, it is the largest county in the state. Approximately 20 percent of residents live in the Greater Omak Area. The county forms a portion of the Okanogan Country. The first county seat was Ruby, Washington, which has now been a ghost town for more than 100 years. Okanogan County was formed out of Stevens County on February 2, 1888. The name derives from the Okanagan language place name uk\u02b7naq\u00edn. The name Okanogan (Okanagan) also refers to the region that encompasses part of southern British Columbia."