Spotswood is a Borough in Middlesex County, New Jersey, United States. As of the United States 2000 Census, the borough population was 7,880. The ZIP code is 08884. Spotswood was incorporated as a borough by an Act of the New Jersey Legislature on April 15, 1908, from portions of East Brunswick Township, based on the approval of a referendum held on May 12, 1908. It was originally called "Spotteswood."