In 1973, $28-million new terminal was built over and around the 1949 structure the new terminal quadrupled the area for public use. The Port embarked on a major expansion plan, designed by The Richardson Associates and lasting from 1967 to 1973, adding a second runway, a parking garage, two satellite terminals and other improvements. Just four years later, it was extended to include another 10 gates, bringing the total to 35. Customs, Immigration, Public Health and the Department of Agriculture. It added eight gate positions, bringing the total to 19, a 12,000 square feet (1,100 m 2) area housing international arrivals and the offices of U.S. The 800-foot (240 m) long Concourse B opened in December 1964. The one-story South Concourse (now Concourse A) opened in 1961, adding another 688 feet (210 m) to the length of the airport. The two-story North Concourse (later dubbed Concourse D) added four gate positions and a new wing 600 feet (180 m) long and 30 feet (9.1 m) wide. In 1966, Scandinavian Airlines began the airport's first non-stop flight to mainland Europe (Pan Am nonstops to London began around 1961).

The first jet flights were Pan Am Boeing 707s to Honolulu via Portland (OR) in late 1959 (Pan Am's timetable for September 27 shows a weekly jet). The April 1957 OAG shows 216 departures a week on United, 80 on Northwest, 35 on Western, 21 on Trans-Canada, 20 on Pan Am, 20 on Pacific Northern (PNA, the successor of Woodley Airways) and 10 on Alaska Airlines. Runway 34L replaced runway 2 around 1970. The extension required the construction of an automobile tunnel for South 188th Street, which opened in July 1961. In June 1951, four runways were at 45-degree angles, between 5,000 and 6,100 feet (1,500 and 1,900 m) long the northeast–southwest and northwest–southeast runways intersected just west of the north–south runway that eventually became today's runway 34R. The official opening ceremony took place on July 9, 1947, in front of a crowd of 30,000. The original terminal was designed by architect Herman A. The first scheduled airline flights were Northwest and Trans-Canada in 1947 Western and United moved from Boeing Field during the next couple of years, and Pan Am moved in 1952–53, but West Coast and successors Air West and Hughes Airwest stayed at Boeing Field until 1971. The Port received $1 million from the Civil Aeronautics Administration and $100,000 from the City of Tacoma to build the airport. military took control of Boeing Field in World War II. The airport was built by the Port of Seattle in 1944 after the U.S. As of 2022, 31 airlines operate at SEA, serving 91 domestic and 28 international destinations.

It is also a hub and international gateway for Delta Air Lines, which has expanded at the airport since 2011.

It is the primary hub for Alaska Airlines, whose headquarters are near the airport. The airport has flights to cities throughout North America, Oceania, Europe, the Middle East, and Asia. airports with similar annual passenger numbers. The entire airport covers an area of 2,500 acres (3.9 sq mi 10 km 2), much smaller than other U.S. The airport, which is the busiest in the Pacific Northwest region of North America, is situated between Portland, Oregon and Vancouver, British Columbia, and is owned by Port of Seattle. It is in the city of SeaTac, which was named after the airport's nickname “Sea-Tac”, approximately 14 miles (23 km) south of Downtown Seattle and 18 miles (29 km) north-northeast of Downtown Tacoma. Seattle–Tacoma International Airport ( IATA: SEA, ICAO: KSEA, FAA LID: SEA), branded as SEA Airport and also referred to as Sea–Tac ( / ˈ s iː t æ k/), is the primary commercial airport serving the Seattle metropolitan area in the U.S.

Encore boston harbor lounge