Seattle-Tacoma International was born of wartime necessity: when the military took over Boeing Field in 1942, the Port of Seattle agreed to build a new civilian airport on a plateau between Seattle and Tacoma, whose city fathers contributed funding in exchange for equal billing in the name.
Scheduled airline service began in 1947 and a proper terminal opened in 1949. The jet age brought satellite concourses and one of America's first underground airport train systems, and Sea-Tac grew steadily as the Puget Sound region boomed with Boeing and, later, the technology industry.
A hard-fought third runway opened in 2008 after years of litigation and one of the largest retaining-wall projects in North America to hold the new embankment. The 2010s transformed the airport's role: Alaska Airlines deepened its largest hub while Delta chose Sea-Tac as its transpacific and European gateway from 2012 onward, igniting rapid growth that made it repeatedly one of the fastest-growing large airports in the country.
The gleaming International Arrivals Facility, with its aerial walkway bridging an active taxilane, opened in 2022. Further expansion of Concourse C and the main terminal is underway to keep pace with demand.