Northumberland County is in Alleghenies & Valleys Pennsylvania. Of the 67 counties in the Independence State, Northumberland County is 48th in terms of its size (477 square miles). There is almost 1,000 acres of residential land for sale in Pennsylvania's Northumberland County based on recent Land Network data. The combined market value of land and rural real estate for sale here is roughly $12 million. The average price of residential acreage for sale in Northumberland County was $475,042. 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.