As the college educated flock to these progressive El Dorados, many factors are cited as reasons: transit systems, density, bike lanes, walkable communities, robust art and cultural scenes. But another way to look at it is simply as White Flight writ large.
Why move to the suburbs of your stodgy Midwest city to escape African Americans and get criticized for it when you can move to Portland and actually be praised as progressive, urban and hip?
In fact, lack of ethnic diversity may have much to do with what allows these places to be “progressive”. It’s easy to have Scandinavian policies if you have Scandinavian demographics.