Clayton is a borough in Gloucester County in the U.S. state of New Jersey. As of the 2020 United States census, the borough's population was 8,807, an increase of 628 from the 2010 census count of 8,179, which in turn reflected an increase of 1,040 from the 7,139 counted in the 2000 census. Jacob Fisler purchased much of the area that is now Clayton, acquiring 6,500 acres of land after the American Revolutionary War. A settlement named Fislertown developed and grew to 36 families by 1812.