Union County is in North New Jersey. Of the 21 counties in the Garden State, 105-square-mile Union County ranks 20th by size. Union County, New Jersey, has almost 8,000 acres of residential land for sale based on recent Land Network data. The combined market value of farms, hunting land and other rural land and acreage for sale here was $12 million. The average price of residential land for sale in Union County was $307,150. Browse all residential land and rural property for sale in New Jersey 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.