These are largest airline hubs in the United States

With almost 43m seats scheduled from Atlanta in the past year, Delta Air Lines has what is indisputably the busiest hub operation in the United States. Not too far behind this is American Airlines’ Dallas-Fort Worth (DFW) operation, with about 37m seats. American’s Charlotte hub is the country’s third largest, according to Cirium, an aviation industry analyst firm.

United’s busiest hub is now Denver, at least based on seats scheduled in the 12 months to April. Unlike the clear leadership of Atlanta in Delta’s network, however, or the leadership of DFW in American’s network, United’s Denver, Chicago, Newark, and Houston networks are all roughly similar in size. Interestingly, Denver is also Southwest’s busiest airport operation.

→ Frontier Airlines begins nonstop flights from Atlanta to 5 destinations

Chicago is the only city that appears three times on the Top 25 list shown below. It’s a major market for United, American, and Southwest, with Southwest serving it from Midway airport. American, however, is greatly shrinking its Chicago presence.

During the past year, United’s San Francisco and Newark hubs have seen the most capacity growth. That makes sense because both are major intercontinental gateways which suffered disproportionately during the pandemic. But United is still smaller now in San Francisco than it was before the pandemic.

The two fastest growing operations since the pandemic have been JetBlue at New York JFK and Southwest at Denver. On the other hand, American’s Philadelphia and Chicago declines represent the biggest retrenchments.