One of the 10 busiest airports in the United States, Phoenix Sky Harbor International Airport served more than 41.1 million passengers in 2014. The airport, which is located about three miles southeast of downtown, serves as a hub for Great Lakes Airlines and US Airways, as well as a focus city for Frontier Airlines and Southwest Airlines. In total, more than 15 carriers fly between Phoenix Sky Harbor and destinations in the United States, Canada, Mexico, Central America and Europe. Phoenix Sky Harbor International Airport has three runways and three passenger terminal with more than 120 gates. Passenger amenities include free WIFI internet, retail shops, fast-food and sit-down restaurants, a museum, ATMs, electronics charging stations, a USO Center, a fitness trail and free cell phone waiting lots.