The three wealthiest places in WA are Hunts Point, Medina, and Yarrow Point. They're also right next to each other and among the most Republican neighborhoods in the Seattle area. I edited a map of Northwestern King County to show them, original map courtesy of some Atlas guy named realisticidealist:
The three relevant localities are circled in black. This particular map is of the 2012 Presidential Election. Notice how Hunts Point, the one in the middle, is the darkest blue. I don't have specific data for any of them, but it'd be cool if someone else could.
Also, a fun fact is that my Congresswoman Suzan DelBene lives in Medina.
By the way, that island to the south of them is Mercer Island, probably the richest actual town in Washington by some measure. They're so bourgeois that they demanded the highway be built under their island, so that us commoners wouldn't sully their neighborhoods. Lol. But I think this map shows the difference between the only somewhat rich and the mega-rich. The only somewhat rich out here still vote Democrat on the federal level (though they sometimes will vote for "socially moderate" Republicans on the local level) while the mega-rich folks in Hunts Point, Yarrow Point, and Medina are straight-ticket GOP partisans.
I think the wealthiest individual precinct is probably the squarish one just below the left side of the circle on the water. Either that one or the one directly above it.
