How to get from Seattle to The Gorge(George) Washington?

Me and my brother are planning to go see Dave Matthews in September up at the Gorge in George Washington, and we can get a flight to Seattle.

But we don't have a way to get to the Gorge. Is there any other ways other than renting a car?How to get from Seattle to The Gorge(George) Washington?
No, not really. There is no public transport to the Gorge. You'd have to find a ride or rent a car. Driving time from Seattle is about 3 hours.
The Gorge is literally in the middle of nowhere. I know for the big concerts people find carpools online like in Craigslist or they might have a section on the Gorge's website. Dave Matthews will be a huge concert so it shouldn't be too hard to find. It is probably the prettiest venues you will ever go to, but unless you have a car, you probably won't get there.How to get from Seattle to The Gorge(George) Washington?
I think the Caravan website had something about carpools. Just ask everyone you can online for a ride and offer them money