Jacksonville, North Carolina, is a city in Onslow County, North Carolina, United States. The 2006 estimated population was 69,688.It is the principal city of and is included in the Jacksonville, North Carolina Metropolitan Statistical Area. Jacksonville is the youngest city in the United States with an average age of 22.9 years old. The low age can be attributed to the large military presence.It is the county seat of Onslow County and the home of the U.S. Marine Corps Camp Lejeune and New River Air Station. Jacksonville is located in North Carolina's Inner Banks region.read full wikipedia reference about Jacksonville, North CarolinaOTHER POPULAR DESTINATIONS IN NORTH CAROLINA