Sullivan County is in Northeast Mountains Pennsylvania. Of the 67 counties in the Keystone State, Sullivan County is 50th in terms of its size (452 square miles). The total value of nearly 1,000 acres of residential land and property recently listed for sale in Pennsylvania's Sullivan County was nearly $4 million. The average price of residential acreage for sale in Sullivan County was $314,600. Browse all residential land and rural property for sale in Pennsylvania to find residential land and properties that suit your lifestyle needs, from existing residential homes and estates to land ready for future residential-property development.