Introduction to Denver International Airport: Denver International Airport (EN) (IATA: DEN, IACO: KDEN) is a civil airport located in Denver, Colorado, United States, and is the largest in the United States and the largest in the world. The second largest airport and has the longest runway in the United States. Currently, Denver International Airport is the fifth largest airport in the United States and the tenth largest airport in the world in terms of traffic volume (47,324,844 passengers in 2006), an increase of 9.1% from 2005. This airport is located northeast of Denver and is operated by the City of Denver.