Of 67 counties in the state, Northumberland County ranks 48th in terms of size (477 square miles). Northumberland County is in Alleghenies & Valleys Pennsylvania. The total value of roughly 1,000 acres of recreational land recently listed for sale in Northumberland County, Pennsylvania, was nearly $1 million. Browse all recreational property for sale in Northumberland County to find the recreational tract that suits your lifestyle needs, from hunting and fishing properties for the outdoor enthusiast to undeveloped acreage ready for future residential-property development. The most common type of land for sale by combined acreage in Northumberland County is house.