Of 21 counties in the state, Middlesex County ranks 13th by size (322 square miles). Middlesex County is in North New Jersey. The total value of 1,000 acres of farms recently listed for sale in Middlesex County, New Jersey, was $1 million. Browse all Middlesex County farms for sale on the Land Network to find the farm, cattle operation, hobby farm or other farm property that's right for your future business or lifestyle needs. The most common type of land for sale by combined acreage in Middlesex County is house.