The Sounder train runs between Pierce and Snohomish counties and is a popular mode of transportation between the major cities of Tacoma, Seattle, and Everett.
Link light rail lines run through downtown Tacoma and between downtown Seattle and SeaTac airport.
The Amtrak Cascades line runs from Vancouver B.C. to Eugene, OR with 16 stops in between, including major cities like Everett, Seattle, Tacoma, Olympia, and Portland (and it’s not as expensive as you might think).