Gloucester County is located in the U.S. state of New Jersey. Its county seat is Woodbury, the oldest town in the county founded in 1683 by Henry Wood. This county is part of he Delaware Valley area. It is located south of Philadelphia and northwest of Atlantic City in New Jersey.Gloucester County has a total area of approximately 337 square miles of which 96% is land and 4% water. As of the 2000 census, there were 254,673 people, 90,717 households, and 67,221 families residing in Gloucester County, NJ.