There was a combined almost $553 million of farms and rural land for sale in Onslow County recently on Land.com. The total size of all Onslow County farms and rural land for sale was around 4,000 acres. Onslow County ranks sixth in the state for the total acreage of land currently advertised for sale. Of all locations in Onslow County with farms and rural land for sale, Jacksonville featured the most land for sale. Onslow County is one of the ten biggest counties in North Carolina (905 square miles). It's located in the Coast North Carolina region of North Carolina.