Land for sale in South Dakota's Pennington County recently totaled almost $87 million and 4,000 acres. Pennington County ranks fifth in the Mount Rushmore State for the total number of acres of land currently advertised for sale. There were two properties listed as sold in Pennington County through the Land Network Comparable Sales Program. This represented a total value of $897,000. Of all land and rural real estate for sale in Pennington County, Rapid City featured the most land for sale. Pennington County is one of the ten biggest counties in South Dakota (2,784 square miles). It's located in the Black Hills & Badlands South Dakota region of the state.