Detroit Metropolitan Wayne County Airport , also called Detroit Metro Airport, or simply DTW, is an airport in Romulus Michigan, near Detroit, and is a major hub for Northwest Airlines and its Northwest Airlink partners Mesaba Airlines and Pinnacle Airlines and it is also a hub for Spirit Airlines. Operated by the Wayne County Airport Authority, the airport has six runways and three terminals. In 2005, DTW served a record 36,389,294 passengers. The Midfield Terminal Parking Structure is an 89-acre 10-level facility, which opened in February 2002. It is one of the largest parking structures in the world. It includes a ground transportation center, pedestrian bridge, two luggage check-in locations, conveyors and bridges to transport luggage, six restrooms, three offices for parking officials, and two electrical substations. The structure can park 11,489 cars in seven user groups. Parking for the L.C. Smith Terminal is offered in a garage known as the Big Blue Deck.