Okanogan County, Washington (Wikipedia)Okanogan County (/ˌoʊkəˈnɑːɡən/) is a county located in the U.S. state of Washington along the Canada–U.S. border. As of the 2020 census, the population was 42,104. The county seat is Okanogan, while the largest city is Omak. Its area is the largest in the state.