Between July 2024 and June 2025, the US Department of Transportation shows that 
Seattle-Tacoma welcomed 51.3 million two-way passengers. With about 52% of the traffic, 
Alaska Airlines was, as everyone knows, very much number one. With nearly a quarter, 
Delta Air Lines was comfortably second.
In the examined 12 months, Seattle had nonstop scheduled passenger flights to over 133 destinations worldwide, of which 37 were international. The airport welcomed various new and returning foreign long-haul carriers during this period. They include China Airlines (July 2024), STARLUX (August 2024; new), Philippine Airlines (October 2024), and SAS (May 2025). Meanwhile, in May 2025, Hawaiian Airlines inaugurated its first long-haul service from Seattle on behalf of Alaska. Alaska is developing Seattle into a global hub.
Seattle’s Top 10 Markets By Total Passengers
The table below is ordered by total passengers. This is the big picture. It includes everyone: local traffic (those who only flew to/from Seattle) and those who connected to another flight (whether in Seattle or another hub or both). Obviously, the local market—those who only flew to/from Seattle—is quite different. In that case, Portland would fall from being the tenth most-trafficked market to the 52nd. Most people drive.
With 1.96 million round-trip passengers, Anchorage was Seattle’s top market at the airport level. Alaska carried 79% of the passengers, followed by Delta with 21%. Alaska’s figures include Hawaiian Airlines, which began Airbus A330-200-operated flights in June 2025. As you can see, Anchorage’s pole position is because a huge 83% of passengers connected elsewhere via Seattle.
|
Total Passengers* |
Seattle To/From… |
Load Factor** |
% Local*** |
|---|---|---|---|
|
1.96 million |
Anchorage |
83% |
17% |
|
1.95 million |
Los Angeles Intl. |
79% |
77% |
|
1.87 million |
Phoenix |
84% |
70% |
|
1.80 million |
Denver |
87% |
53% |
|
1.83 million |
Las Vegas |
83% |
71% |
|
1.67 million |
Dallas/Fort Worth |
88% |
57% |
|
1.59 million |
San Francisco |
80% |
69% |
|
1.55 million |
Chicago O’Hare |
89% |
54% |
|
1.20 million |
San Diego |
82% |
77% |
|
1.10 million |
Portland |
76% |
14% |
|
* July 2024-June 2025. US DOT |
* All airlines. US DOT |
*** All airlines. US DOT |
Los Angeles International Was Seattle’s #1 Local Market
In the examined 12 months, 1.95 million passengers flew between Seattle and Los Angeles. More than three in four people—about 1.50 million—only flew between the two airports. They didn’t go elsewhere. Phoenix was the second most popular local market.
Frontier inaugurated Seattle-Los Angeles flights in December 2024. This was influenced by Spirit announcing the end of its operation in May 2025, which was the month in which the troubled airline pulled out of Seattle entirely. This is despite achieving an 89% seat load factor which, as always, is just one performance metric and should not be considered in isolation.
|
Load Factor* |
Airline |
|---|---|
|
89% |
Spirit |
|
82% |
Frontier |
|
81% |
Alaska |
|
81% |
American |
|
78% |
Delta |
|
72% |
United |
|
* US DOT, July 2024-June 2025, for the total traffic |
Between December 2024 and May 2025, the market had six operators. It was one of the US’s few airport pairs with that many airlines. Spirit’s exit, due to its major ongoing challenges, means five airlines now operate. There will be an average of 20 daily departures in October.
Taipei Has Overtaken Vancouver As The #1 International Market
Sticking with total traffic, Seattle-Taipei had 650,000 round-trip passengers in the analyzed period. It overtook Vancouver (622,000), which had been first for many years.
The Taiwanese capital’s jump was because of the entry of Delta in June 2024, China Airlines’ return in July, and STARLUX’s launch the following month. They joined EVA Air. The market now has a record four airlines, with up to five daily flights.
