The concept of 'fortress hubs' in the airline industry is not exclusive to the United States, although it remains a prominent feature of its aviation market. Globally, airlines like Ethiopian Airlines and Turkish Airlines maintain dominant shares at their respective home airports.
In the US, a fortress hub is typically defined as an airport where an airline operates at least 70% of flights. This dominance often leads to higher fares for point-to-point passengers but provides competitive pricing for connecting flights due to increased competition.
According to Cirium Diio data, ten US airports are classified as fortress hubs for December. Charlotte tops the list with American Airlines operating 88% of its flights. Other notable entries include Dallas/Fort Worth with 84% by American Airlines and Houston Intercontinental with 79% by United Airlines.