The total value of land for sale in Multnomah County recently on Land.com was approximately $145 million. This represents almost 1,000 acres of farms, ranches, and rural real estate for sale in Multnomah County. Multnomah County ranks 23rd in the Beaver State for the total number of acres of land currently advertised for sale. Among cities in Multnomah County with land and rural real estate for sale, Portland had the most land for sale. Multnomah County is Oregon's 36th biggest county (465 square miles). It's located in the Portland Metro Oregon region of the state.