The Port Authority operates the Port Newark–Elizabeth Marine Terminal, which handled the third-largest volume of shipping among all ports in the United States in 2004, and the largest on the Eastern Seaboard. The Port Authority also operates six bi-state crossings: three connecting New Jersey with Manhattan, and three connecting New Jersey with Staten Island. The Port Authority Bus Terminal and the PATH rail system are also run by the Port Authority, as well as LaGuardia Airport, John F. Kennedy International Airport, Newark Liberty International Airport, Teterboro Airport and Stewart International Airport. The agency has its own 2,232-member Port Authority Police Department.