There was a total of almost $85 million of land for sale in New Hampshire's Sullivan County recently on Land.com. The total acreage of all Sullivan County land for sale was almost 3,000 acres. Sullivan County ranks 10th out of 10 counties in the Granite State for the total number of acres of land currently advertised for sale. Claremont had the most land for sale. Sullivan County is one of the ten largest counties in New Hampshire (552 square miles). It's located in the Central New Hampshire region of the state.