Demographically, Oregon is just New England and the Mid-Atlantic States transported to the Pacific Coast. They've always voted that way, too. When political guru Kevin Phillips was a teenager, he did a political voting-pattern map of the United States by county. When he was done, you could see strings and streamers of color flowing east to west on the map. The map was interesting enough that Richard Nixon took a look, and later gave Phillips a job.
Oregon being due west of Massachusetts and New York, Oregonians act like Taxachusetts commissars and New Yorkers.