Due to the increase in Chinese manufacturing and Japanese automobiles, those ethnic groups migrated to the West Coast including WA,OR,HI and CA. Along with the Mexican migration those states went left.
While true, they have nothing to do with the Pacific coast of Oregon and Washington. The coast is very white with smatterings of native american tribes. I don't know about Oregon, but the coastal counties in WA had been the center for Democrat strength the longest in WA (before Seattle).