Located eight miles northwest of downtown Miami, Miami International Airport (MIA) is a major gateway to Latin America and the 11th-busiest airport (when measured by passenger traffic) in the United States. In 2014, 40.9 million travelers passed through MIA. The airport is a hub for American Airlines and a focus city for Avianca, Frontier Airlines, LAN Airlines and TAM Brazilian Airlines. In total, more than 50 commercial carriers operate at the airport, and non-stop flights are available to destinations across the United States, as well as points in the Caribbean, Mexico, Central and South America, Canada, Europe and Asia. Passengers flying through MIA have a number of ground transportation options. These include Metrobus and Metrorail, Tri-Rail, taxis, limousines, shared-ride shuttles and free hotel shuttles. More than 15 rental car companies have a presence at the airport's Rental Car Center.