Washington's current map strikes me as needlessly messy. There are multiple incidents of two districts sharing the same county, not one district is fully contained within King County, and I don't think WA-01 is even contiguous by road. I don't know a lot of background info about dynamics of the last redistricting cycle there, but I would expect better from a commission.
Anyway, here's what I came up with:
1: Clinton +7
2: Clinton +36
3: Trump +8
4: Trump +23 (39% Hispanic)
5: Trump +13
6: Clinton +12
7: Clinton +77
8: Clinton +5
9: Clinton +40 (48% white)
10: Clinton +13
Not much change from a partisan standpoint, but a lot cleaner. Northern WA gets its own seat, as does Pierce County. All of Seattle is in the 7th, and the 9th is all-King County suburbs while still being minority-majority. As was mentioned, there's no good way to cross the Cascades, so I figured sticking with I-90 made the most sense. For all the oddities of the current map, I think the 8th district is about as sensible as it can be.
(I double-crossed 4 and 5 here because of the wacky precincts in Walla Walla, which is of course not necessary.)
This is one of the best maps I've seen. People really need to stop butchering the area between Everett and Bellingham.
