Seattle-Tacoma Airport Welcomes 51.3 Million Passengers in 2024-2025

Seattle-Tacoma International Airport experienced significant growth in passenger traffic, welcoming 51.3 million two-way passengers between July 2024 and June 2025, according to the US Department of Transportation. Alaska Airlines firmly established itself as the leading carrier, accounting for approximately 52% of total traffic, while Delta Air Lines secured the second position with nearly 25% of the market share.

During this period, Seattle-Tacoma provided nonstop scheduled flights to over 133 destinations worldwide, including 37 international routes. The airport saw the introduction of several new and returning long-haul carriers, enhancing its global connectivity. Notable additions included China Airlines in July 2024, STARLUX in August 2024, Philippine Airlines in October 2024, and SAS in May 2025. Additionally, Hawaiian Airlines launched its inaugural long-haul service from Seattle in collaboration with Alaska Airlines in May 2025, further solidifying Seattle’s role as a global hub.

Top Passenger Markets from Seattle

The airport’s top markets by total passengers highlight the extensive reach of Seattle-Tacoma. Anchorage emerged as the leading market, with 1.96 million round-trip passengers, of which Alaska Airlines carried 79%. A substantial 83% of these passengers connected to other flights, illustrating the airport’s importance as a transit hub.

Los Angeles International Airport ranked as Seattle’s most significant local market, with 1.95 million passengers traveling exclusively between the two cities. About 1.50 million of these passengers did not connect to other flights. Phoenix followed closely as the second most popular local market.

The data reveals a competitive landscape among airlines. The load factor, which indicates the percentage of available seating capacity that is filled with passengers, varied across carriers. Spirit Airlines recorded a load factor of 89%, while Alaska Airlines and Delta Air Lines reported load factors of 81% and 72%, respectively.

International Travel: Taipei Surpasses Vancouver

In the international arena, the Seattle-Taipei route saw a remarkable surge, with 650,000 round-trip passengers, surpassing Vancouver’s 622,000. This shift can be attributed to the introduction of Delta Air Lines in June 2024, alongside the return of China Airlines and the launch of STARLUX in the subsequent months. With four airlines now servicing the Taipei route, including EVA Air, there are up to five daily flights available, reflecting a robust demand for travel to Taiwan.

Overall, the growth in passenger numbers at Seattle-Tacoma International Airport underscores its expanding role as a major travel hub in the United States. With increased connectivity and a diverse range of destinations, the airport is poised to continue its upward trajectory in the coming years.