Law enforcement in Massachusetts
Many municipalities of Massachusetts have their own police departments, as do many colleges and universities. Though most county governments have been abolished, each county still has a Sheriff's Department which operates jails and correctional facilities and service of process within the county. The Massachusetts State Police have statewide jurisdiction, including full criminal law enforcement, Highway Patrol and traffic enforcement, investigation, and special air, marine, and tactical response. They share concurrent jurisdiction with municipal and institutional departments, and have primary jurisdiction in towns that have no local police force. State police divisions ("Troops") are dedicated to  the Massachusetts Turnpike and Logan International Airport, and since 1992 the state police have had primary responsibility for the state capital building, facilities of the Registry of Motor Vehicles, and DCR parks. State police also have sole authority under state law for investigating homicides, except for Boston, Worcester, and Springfield. Though fully deputized in 175 cities and towns, Massachusetts Bay Transportation Authority Police have primary responsibility for MBTA facilities and commuter railroads statewide, and share enforcement duties (such as writing tickets for parking in bus stops) with local and state police, especially in remote areas and on Massport property, which  is policed by the Massport Police. The Massachusetts Environmental Police are also independent of the State Police.The horse mounted Boston Park Rangers patrol the hubs parks. The US Coast Guard Station in Boston provides Law enforcement services in the ocean surrounding Massachusetts. Harbormasters in the area enforce the law in Massachusetts harbors. Massachusetts Army National Guard has reserve CID agents who can investigate breaches of military and Federal law. At the same time the Massachusetts Fire Marshall has detectives who investigate suspicious fires and explosions. District Attorney offices often have officers or troopers assigned to them to assist with  prosecutions. Railroad police also have authority on railroad property. Railroad and ferry company employees may be appointed as special state police officers under Massachusetts state law, with jurisdiction on company property and vehicles. Federal regulations extend the authority granted by one state to a railroad police officer to all the states in which that railroad has property.