I've lived in Washington for about eight years, now, and I'm tired of people east of the Cascades bleating about how Western Washingtonians have the East under our thumb.
The tl; dr version is that King county taxpayers (which includes Seattle) receive $0.62 back in benefits for every dollar they pay to the state, whereas people in Republican-leaning counties (i.e the eastern part of the state) get back an average of $1.40 for every buck they kick into state coffers.
A good bit of that extra money Eastern Washington gets back goes towards things like maintaining irrigation canals that make it possible for farmers to grow food for the rest of the state. Some of it goes towards maintaining the dams that provide a lot of power to the state. And some of it goes towards cleaning up Hanford - the federal government hasn't picked up the entire tab for that, even though it should. Some of it goes towards education, of course. --Let's be honest, agriculture has brought a lot of immigrants to that side of the State, and the Pasco School District, for example, has the highest percentage of ESL students than any other school district in the state.
Don't get me wrong, I don't agree with the political leanings of much of Eastern Washington, and even now I have no desire to ever move back there, but having grown up there, I can certainly attest to the fact that things are much more complex than you seem to believe.
Could you explain to someone completely unfamilliar with the internal economies of Washington state why the western portion of the state is forced to buy food from the western portion, or why it couldn't buy the electricity from a separate state of Eastern Washinton?
The regional issues such as education and the Hanford site...are regional issues, if I'm not putting too sharp a realpolitc edge on my examination.
The people in the Eastern part of the state are more than welcome to split off if they want to, seeing how us Seattle liberals underwrite their existence (cf. http://slog.thestranger.com/slog/archives/2011/01/25/since-r..., http://slog.thestranger.com/slog/archives/2011/01/25/welfare..., and http://slog.thestranger.com/slog/archives/2011/01/27/6495426...)
The tl; dr version is that King county taxpayers (which includes Seattle) receive $0.62 back in benefits for every dollar they pay to the state, whereas people in Republican-leaning counties (i.e the eastern part of the state) get back an average of $1.40 for every buck they kick into state coffers.