United Airlines is one of the world’s largest carriers in terms of fleet size, passengers carried, destinations served, and annual revenue. The airline operates out of its seven hubs in the continental United States, including Chicago O’Hare (ORD), Denver International (DEN), Houston George Bush International (IAH), Los Angeles (LAX), Newark Liberty (EWR), San Francisco (SFO), and Washington Dulles (IAD). The airline operates frequent flights from all its hubs to Tampa International Airport (TPA) in Florida, one of United’s major southern destinations.