Denver International Airport (IATA: DEN) is an airport in Devner, Colorado, USA. With an area of 33,531 acres, it is the largest airport in the United States by total area. Runway 16R/34L is the longest public runway in the United States, with a total length of 16,000 feet (4,877 m). With 54 million passengers as of 2015, DEN is the 18th busiest airport in the world and the 6th busiest airport in the USA according to passenger traffic. It is also the airport that provides the third largest local line connection in the country. The airport's 133 gates are distributed along linearly arranged separate but internally connected terminals (A, B & C).
The airport serves as the main hub for Frontier Airlines and Great Lakes Airlines. It is also United Airlines' fourth largest hub, with 375 flights to 141 destinations daily. The airport is also Southwest Airlines' 4th most used and fastest growing market, with 60 destinations and 190 daily flights.
There are many public transportation options to reach the terminal, including: private buses, suburban trains, hotel buses, limousines, mountain carriers, public transport buses, shared shuttles and taxis. Many services reach the fifth level terminal from the Hotel and Transit center via public transport buses. Private vehicles arrive from the East and West sides of the terminal; depending on the airline, they drop off at the sixth level and board at the fourth level.
The Regional Transportation District (RTD) company operates three lines within the framework of airport express bus services; The express line is skyRide, and there are also lines called Express and Limited. These lines provide transportation to various points between DIA and the Denver-Aurora and Boulder metropolitan areas. RTD also operates the University of Colorado A Line and commuter rail between Union Station in downtown Denver and the airport.