Land for sale in Day County recently totaled $13 million and almost 1,000 acres. Day County ranks 20th out of 66 counties in South Dakota for the combined amount of land currently advertised for sale. Webster had the most land for sale. Day County has a large agricultural economy, with 693 farms recorded in the county during the latest U.S. Census. Farming activities in Day County generate annual revenues of $9 million, most of which is from crops. Day County is the 28th biggest county (1,091 square miles) in South Dakota. It's located in the Glacial Lakes & Prairies South Dakota region of the state.