International Airport (IATA: DEN, ICAO: KDEN, FAA LID: DEN), often referred to as DIA, is an airport in Denver, Colorado
. By land size, at 53 square miles (140 km2), it is the largest international airport in the United States
, and the third largest international airport in the World
after King Fahd International Airport and Montréal-Mirabel International Airport. Runway 16R/34L is the longest public use runway in the United States. From January to September 2011, Denver International Airport was the 10th-busiest airport in the world by passenger traffic with 39,953,117 passengers.
Denver International Airport is the main hub for low-cost carrier Frontier Airlines and commuter carrier Great Lakes Airlines. It is also the fourth-largest hub for United Airlines. The airport is a focus city for Southwest Airlines. Since commencing service to Denver in January 2006, Southwest has added over 40 destinations, making Denver its fastest-growing market. Denver International Airport is the only airport in the United States to have designed and implemented an ISO 14001-certified environmental management system that covers the entire airport.
The airport's distinctive white Teflon-coated fiberglass roof is aesthetically designed to be reminiscent of the snow-capped Rocky Mountains in winter. The catenary steel cable system, similar to the Brooklyn Bridge design, supports the roof. DIA is also known for a pedestrian bridge connecting the terminal to Concourse A that allows travelers to view planes taxiing directly underneath and provides sweeping views of the Rocky Mountains to the West and the high plains to the East.