Denver International Airport (DEN), opened on February 28, 1995, is a major global hub on the Great Plains, featuring the longest public-use runway in North America (16R/34L at 16,000 feet). It replaced the cramped Stapleton International Airport after a massive project championed by Mayor Federico Peña, who secured an Adams County annexation in 1988 and $500 million in federal funding to solidify its role as a national air hub. Serving as the largest operating hub for United, Frontier, and Southwest Airlines, DEN connects to over 230 destinations and is Colorado’s largest employer, contributing an estimated $47.2 billion annually to the state's economy. By 2023, it handled nearly 77.8 million passengers (6th busiest worldwide, 3rd in the US), and it set an all-time record in 2025 with over 82.4 million travelers. Despite initial skepticism over its remote location 25 miles from downtown, the airport's midcontinent position and massive scale have kept it among the world’s top ten busiest airports every year since 2000.