The sixth-busiest airport in the United States and the busiest in North America when measured by international passenger traffic, John F. Kennedy International Airport (JFK) is located about 12 miles southeast from downtown Manhattan. It is one of three major airports serving the New York metropolitan area. More than 90 carriers operate at the airport, flying non-stop to destinations within North America, as well as points in South America, Europe, Africa, Asia and Australia. American Airlines, Delta Air Lines and JetBlue Airways have designated JFK as a hub. The airport has four runways and six terminals with a total of 128 gates. Ground transportation options at JFK include the AirTrain, which connects to many other modes of public transportation, buses, taxis, limousines, shared-ride shuttles and rental cars. Helicopter service to downtown Manhattan is also available.