Of 105 counties in the Wheat State, Washington County ranks 30th in terms of size (898 square miles). Washington County is in Tallgrass Prairie Kansas. Kansas's Washington County includes about 1,000 acres of farms for sale based on recent Land Network data. The combined market value of land for sale here was around $1 million. Browse all Washington County farms for sale on the Land Network to find the farm, cattle operation, hobby farm or other farm property that's right for your future commercial or individual needs. By overall acreage, house is the most common type of land for sale in Washington County.