From Sound Transit:
The State Fair has a new ride! On Saturdays, Sept. 14 and 21, you can take a Sounder train to Puyallup and home again. The Fair offers free shuttle service to and from Puyallup Station.
From King and Pierce county stations: Buy tickets from ticket vending machines at stations; make sure to choose Puyallup as your destination station. Regular fares apply.
From Snohomish County stations: Starting Sept. 1, buy special event tickets to the Washington State Fair from ticket vending machines at stations. Take Sounder to Seattle's King Street Station, where you'll change trains to continue to Puyallup. (Don't worry; it's just a few steps across the train platform.) Your transfer is free when you buy a special event ticket or just use your ORCA card.
For more schedule flexibility, ST Express Route 578 runs between Seattle and Puyallup seven days a week.
Find Fair hours, admission fees and other details online at thefair.com.
See schedules and more on the Sound Transit website.