Seattle–Tacoma International Airport (Sea–Tac Airport or Sea–Tac) is the largest airport in the Pacific Northwest region of North America. The airport is located in the eponymous city of SeaTac, Washington, approximately twelve miles south of downtown Seattle, and is the primary airport for the Seattle metropolitan area. The airport has flights to cities throughout North America, Europe, the Middle East, and Asia. It is the main hub for Alaska Airlines and its regional subsidiary Horizon Air, whose headquarters are near the airport. It is a hub and international gateway to Asia and Europe for Delta Air Lines, which has expanded at Sea-Tac since 2011. In 2014 the airport served over 37 million passengers. The airport is the largest generator of vehicle trips in the state, and its 13,000-car parking garage is North America’s largest parking structure under one roof. The top airlines at the airport by passenger count in 2014 were Alaska Airlines (51.46%), Delta Air Lines (15.53%), United Airlines (8.23%), and Southwest Airlines (8.03%).