- Jefferson County, Washington has 1,803.7 square miles of land area and is the 18th largest county in Washington by total area. Jefferson County, Washington is bordered by Grays Harbor County, Washington, Kitsap County, Washington, Clallam County, Washington, Island County, Washington, Mason County, Washington, and San Juan County, Washington.
- 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.