Magnolia is a borough in Camden County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 4,341, reflecting a decline of 68 from the 4,409 counted in the 2000 Census, which had in turn declined by 452 from the 4,861 counted in the 1990 Census.Magnolia was incorporated as a borough by an act of the New Jersey Legislature on April 14, 1915, from portions of the now-defunct Centre Township, and parts of Clementon, based on the results of a referendum held on May 12, 1915. The borough was named for magnolia trees that grow in the area.