Washington County is part of the the Chehalem Mountains AVA wine region, which sits on a series of sedimentary ridges that provide diverse soils and growing conditions at slightly higher altitudes than other Willamette Valley vineyards. Some 150 vineyards are located throughout the hilly countryside, comprising three counties—Yamhill, Washington and Clackamas—which frame the southwestern suburbs of the Portland metropolitan area. A total of around 4,000 acres were listed for sale in Washington County, Oregon, recently; the combined value of all Washington County land and rural real estate for sale was approximately $163 million. Washington County ranks 16th in the Beaver State for the combined amount of land currently advertised for sale. Hillsboro had the most land for sale. From an economic perspective, manufacturing and related services are the main sectors in Washington County. Washington County is the 31st biggest county (726 square miles) in Oregon. It's located in the Portland Metro Oregon region of Oregon.