Of 66 counties in the Mount Rushmore State, Sully County ranks 29th by size (1,070 square miles). Sully County is in Great Lakes South Dakota. There is nearly 17,000 acres of commercial land and property for sale in South Dakota's Sully County based on recent Land Network data. The combined market value of ranches, farms, hunting land and other rural land and acreage for sale here is $172 million. Browse all Sully County commercial acreage for sale on the Land Network to find your next commercial property or land investment. The most common type of land for sale by combined acreage in Sully County is undeveloped land.