That map is for the entire metropolitan area, and then some. Consider [0], the neighborhoods of Seattle itself, and then look at the island of blue color in the middle of downtown and the affluent neighborhoods of Magnolia, Ballard, and Queen Anne.

Across from Seattle, across Lake Washington, you can also see the majority-blue suburb of Bellevue.

[0] https://northwesturbanist.files.wordpress.com/2016/08/seattl...