‍DALLAS — In the shadows of the Cascade Mountains, Seattle-Tacoma International Airport (SEA) is the gateway to the Pacific Northwest of the United States and the last stop before Alaska for many.

Having seen 52.6 million passengers in 2024, Seattle-Tacoma, or “SeaTac” for short, is currently the 14th busiest airport in the US, situated between Orlando International (MCO) and Charlotte Douglas (CLT). 

SeaTac is one of many airfields in the region, with the Pacific Northwest having some of the richest connections in the world to aviation and the broader technology industry. This primarily comes thanks to the Boeing aircraft company having three of their most important production facilities here, and other multi-billion dollar companies such as Google, Microsoft, Starbucks, and Amazon calling Seattle home.

But what made Seattle-Tacoma the airport it is today? In this post, we will explore what brought SeaTac to prominence.

Early Years

Unlike many airports of the time, Seattle’s airport was a clean sheet design from the ground up. Where other airports, such as those in San Francisco or Boston, were initially designed around grass strips and developed through military involvement during the war, SeaTac was created with all the advancements the war brought already in mind.

The need for an airport arose in the early 1920s. It was proposed as a joint operation shared between the ports of Seattle and Tacoma; however, these plans were initially rejected.

After legislative changes in 1941, allowing the formation of municipally run airports, reignited interest in the project. Funding was then granted from the Civil Aeronautics Board of US$1 million. 

Development began on January 2, 1943. The airport would have four intersecting runways to counter crosswind operations and would see its first ceremonial landing on October 31, 1944, from a United Airlines Douglas DC-3 carrying public officials. Low-level passenger operations did begin in 1945, but they were quashed by the United States military’s need to use the field as a pre-delivery staging area for B-29 bombers. It would take another two years before the airport would open to passengers in earnest.

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With a newly completed passenger terminal, SeaTac officially opened its gates to passengers on September 1, 1947; however, it wasn’t dedicated until July 9, 1949. On this day, the airport was opened to the public and hosted around 30,000 people to witness the event.

SeaTac was hailed as “America’s most advanced airport”, with its long runways and spacious terminal for the time. For the technologies of the era, the airport seemed to be future-proofed. At this time, the airport was served by numerous recognisable brands, including Northwest Airlines, Western Airlines, Pan Am, Alaska Airlines, and Trans-Canada Airlines by 1951. 

The intersecting runway layout soon became redundant during the mid-1950s as aircraft became more able to handle crosswind conditions. The north-south runway, runway 16/34, became the airport’s primary direction. It was lengthened three times during that decade until it reached 10,200ft, or 3,100m, in anticipation of the era’s newfound jet airliners, which were quickly gaining traction. 

The 1950s were a big decade of growth at SeaTac, with the addition of on-site parking and a customs and air mail section. Trans Pacific services would arrive in 1959 with the inauguration of Japan Airlines' service from Tokyo.

1960s Onward

The 1961 World Fair, which Seattle was hosting, was the airport’s excuse to modernise yet again, highlighting what Seattle had to offer right from when passengers arrived. And the fair attracted some of the world’s biggest names, including Prince Phillip, President Kennedy, Elvis, and others.

To prepare for the fair and to future-proof the airport further, SeaTac lengthened its runways by an additional 800 metres, or 2600 feet, and opened a new concourse with wider gates to allow for jet traffic. That jet traffic came in October 1961 with a Boeing 707 service connecting the airport with Honolulu.

The airport would continue to expand throughout the 1960s, expanding its international footprint. Scandinavian Airlines launched service here in 1966, using a polar routing, marking its first European service.

The beginning of the 1970s saw SeaTac be the origin of one of the world’s greatest unsolved crimes. On the afternoon of the 24th of November 1971, Northwest Airlines Flight 305, a Boeing 727-100 with 42 passengers and crew on board, left Seattle, bound for Portland, Oregon. On board was a passenger by the name of Dan Cooper. He had bought a one-way ticket at the airport for the flight in cash and was carrying a black attaché briefcase.

Once airborne, he proceeded to hijack the aircraft. It would land in Portland without incident, and his ransom was US$200,000, as well as a parachute for the release of the passengers, which he received. He then ordered the plane back into the air, strapped the parachute on, and proceeded to jump out of the plane over Washington state, using the 727’s rear access stairs. He was never heard from again, and the mystery of what happened to the man, D.B. Cooper, has endured to this day.

Even with the employment downturn in Seattle in the 1970s, the airport still saw major expansions. The decade saw the addition of two satellite terminals, doubling the public road infrastructure and adding a car park just to meet demand. Former airport director Otis Dunham stated, "Almost every week, we changed how people drove, walked, or the way the airplanes taxied, for two years.” Furthermore, the airport added a subway rail connection between the two terminals. These driverless trains were the first of their kind in the United States. By the end of this expansion, SeaTac was running like a finely tuned engine.

By the late 1980s, SeaTac had two runways and began feeling the strain. Due to the dramatic increase in the use of regional airlines and aircraft and Seattle’s growing prominence as a cargo hub, proposals for a third runway were drafted. The most suitable spot for this third runway was determined to be to the west of the existing two, but was met by backlash from the towns affected, such as Des Moines, Federal Way, and Tukwila, among others.

After finding no other suitable spots, the port authority approved plans for the third runway west of the current two in 1996. However, construction could not begin until all appeals against it were dropped. Ground wasn’t broken on this project until 2004, and it wouldn’t be completed until 2008, at US$1.1 billion.

More Recently

More recently, SeaTac has been showing its age. Again, passenger numbers have crept beyond what the airport was designed for. With many buildings dating back to the 1970s, the port authority announced plans for a new International Arrivals Facility in 2017. The facility, which opened three years behind schedule in 2022, is built along the east side of the domestic concourse. It consists of 16 wide-body gates and four narrow-body ones. The project’s most eye-catching feature is its 226-metre or 85-foot tall bridge, spanning above the taxiway. This project cost US$968 million.

Today, the airport still has many construction projects underway to accelerate the passenger experience and hopes to be ready for the 2026 World Cup, which the United States is hosting, along with Canada and Mexico cities. These upgrades include more efficient TSA security equipment, with hopes to scan up to 600 extra passengers an hour. Furthermore, new baggage systems are being implemented to speed up the passenger experience again, and new space for shopping and eateries is being made available. All this is part of a 5 billion upgrade in time for the World Cup.

Today, the Future

Today, the airport is a significant hub for SkyTeam and oneworld airlines, through Delta Airlines and Alaska Airlines. This is mainly due to the city’s major tech industries and advantageous geographical position in Asia and Alaska. Alaska and Delta airlines hold 49 and 20% market share, respectively, serving the airport’s busiest destination, Anchorage, Alaska, for which SeaTac has become a gateway.

SeaTac is the busiest airport in the American Northwest and will likely remain so. The Seattle area could grow by another million people by 2035, and the airport has to be ready. Over 30 projects are currently in the planning phase or are already under construction. These include a new, more streamlined baggage handling system, a new 19-gate terminal, and another automated rail system to move passengers between terminals. The airport could be a construction site for another 10 to 20 years before completing all its projects. 

In the meantime, though, it has become clear that Seattle Tacoma’s managers have the passengers in mind in order to make the airport an acceptable first impression of the United States. Having come from humble beginnings, the airport’s staff have not shied away from the future and the challenges that await them. SeaTac has always strived to be a world-class airport, and it appears to be making every effort to succeed in its mission.