There was a combined approximately $14 million of farms, ranches, and rural real estate for sale in Riley County recently on Land.com. The total of all Riley County land for sale was almost 1,000 acres. Riley County ranks 57th in the Sunflower State for the total number of acres of land currently advertised for sale. Manhattan had the most land for sale. From an economic perspective, government and state-level services contribute most to Riley County's overall GDP. Riley County is the 81st biggest county (622 square miles) in Kansas. It's located in the Tallgrass Prairie Kansas region of the state.