The Greenbelt Police Department (GPD) is the primary law enforcement agency servicing a population of 21,972 http://factfinder.census.gov/servlet/SAFFPopulation?_event=Search&_name=greenbelt&_state=04000US24&_county=greenbelt&_cityTown=greenbelt&_zip=&_sse=on&_lang=en&pctxt=fph Census Bureau within 6 sqmi of the city of Greenbelt.