Two airports serve Philadelphia: the Philadelphia International Airport (PHL), straddling the southern boundary of the city, and the Northeast Philadelphia Airport (PNE), a general aviation reliever airport in Northeast Philadelphia. Philadelphia International Airport provides scheduled domestic and international air service, while Northeast Philadelphia Airport serves general and corporate aviation. In 2013, Philadelphia International Airport was the 15th busiest airport in the world measured by traffic movements (i.e. takeoffs and landings). It is also the second largest hub and primary international hub for American Airlines.

Name the main airport?