Riley County is in Tallgrass Prairie Kansas. Of the 105 counties in the Wheat State, 622-square-mile Riley County ranks 81st by size. The total value of about 1,000 acres of residential land and property recently listed for sale in Riley County, Kansas, was nearly $10 million. The average price of residential acreage for sale in Riley County was $713,069. Browse all residential land and rural property for sale in Kansas to find residential land and properties that suit your lifestyle needs, from existing residential homes and estates to land ready for future residential-property development.