Boulder is a home rule city and the county seat of Boulder County, Colorado, United States. It is the largest city in Boulder County, with a population of 108,250 at the 2020 United States census, making it the 12th-most populous city in Colorado. Boulder is the principal city of the Boulder, CO Metropolitan Statistical Area and part of the Front Range Urban Corridor.

Denver International Airport, locally known as DIA, is an international airport in the Western United States, primarily serving metropolitan Denver, Colorado, as well as the greater Front Range Urban Corridor. At 33,531 acres, it is the largest airport in the Western Hemisphere by land area and the second largest on Earth, behind King Fahd International Airport. Runway 16R/34L, with a length of 16,000 feet, is the longest public use runway in North America and the seventh longest on Earth. The airport is 25 miles (40 km) driving distance northeast of Downtown Denver, 19 miles (31 km) farther than the former Stapleton International Airport, the facility DEN replaced: the airport is actually closer to the City of Aurora than central Denver, and many airport-related services, such as hotels, are located in Aurora.