The 3rd controlling county is Pierce, not Whatcom.
Somebody else said that.
Nope, I meant Whatcom. Pierce has far more Republicans and conservatives and GENERALLY votes, at worst, moderate. The reason for that is the concentration of military and military retirees.
King, Snohomish, and Whatcom are full of uber-liberals.
(Yes...I know Snohomish has Naval Base Everett, but despite that, the county has a bad tendency to vote very liberal in pretty much every election. Pierce, not so much.)