Transatlantic and transpacific dominance
New York to London is the busiest international route due to large populations on both sides, time zones that enable business travel, and premium pricing. Los Angeles to Tokyo reflects trade between the US and Japan. The Middle East has become a major hub: Dubai connects North Europe to South Asia efficiently, making it a nexus for long-haul routes. These routes concentrate air traffic and create capacity bottlenecks.
Hub-and-spoke economics
A passenger flying from London to Sydney may route through Dubai or Singapore rather than direct, because hub airlines consolidate smaller routes. This concentrates traffic at major airports, enabling cheaper connections through economies of scale but creating congestion and delays. Geographic distance alone does not determine traffic; economic development, airline networks, and historical traffic patterns matter equally.