Sponsored Topics. Madison is a borough in Morris County, New Jersey, in the United States. As of the 2000 United States Census, the population was 16,530. It also is known as The Rose City. Madison is located at 40°45′32″N 74°24′58″W / 40.758750°N 74.416098°W / 40.758750; -74.416098 (40.758750, -74.416098).