Michigan's busiest airport, Detroit Metropolitan Wayne County Airport (DTW) served about 32.5 million passengers in 2014. The airport serves southeast Michigan, southwest Ontario and northwest Ohio. It features six runways and two terminals with a combined total of 145 gates. More than a dozen airlines fly to DTW, including Delta Air Lines, which uses it as a hub, and Spirit Airlines, which has designated it as a focus city. Passengers can fly non-stop to Detroit from destinations in North America, South America, Europe, the Middle East and Asia. Ground transportation options at Detroit Airport include taxis, pre-reserved limousines, hotel courtesy shuttles and public buses that serve the Detroit and Ann Arbor metropolitan areas. About 10 rental car companies also have an onsite presence at DTW.