From Transit.Wiki

Seattle is the largest city in Washington and the Pacific Northwest. Seattle, along with other cities like Bellevue, Tacoma, and Everett, make up the entire metropolitan region.

Located in King County.

Web site
Local transit
Regional rail stations
Intercity bus

Bellair Airporter Anacortes-San Juan route Anacortes - SeaTac

Bellair Airporter Central Washington route Yakima - SeaTac

Bellair Airporter I-5 Corridor route Blaine - SeaTac

Flixbus at International District/Chinatown

Flixbus at The Ave

Flixbus at Seattle Greyhound

Greyhound at Seattle Greyhound

Northwestern Trailways Tacoma - Spokane - Boise

Quick Shuttle Vancouver BC - SeaTac Airport

Travel Washington Dungeness Line Port Angeles - SeaTac Airport