Wondering What Terminal is Southwest Airlines at DIA? Southwest Airlines operates from Terminal W at the bustling Jeppesen Terminal at Denver International Airport, making travel convenient. Southwest provides a pleasant ride through DIA, from easy check-in on the West Side of the main terminal to quick gate access via the airport's rapid train system. Terminal W is jam-packed with food options, shopping outlets, and comfy lounges, making it ideal for unwinding before your trip. Southwest's excellent setup at DIA's Terminal W ensures a hassle-free travel experience.