Hammond is the largest city in Tangipahoa Parish, Louisiana, United States. The population was 20,049 at the 2009 census. It is home to Southeastern Louisiana University. The city was the home base for production of the first season of the NBC television series In the Heat of the Night. Hammond is the principal city of the Hammond Micropolitan Statistical Area, which includes all of Tangipahoa Parish. Former U.S. Representative James H.