Portland, ME and Portland, OR have hard core Dem governments, and have for years. And if you cross the river to Windsor, ON, you have a government run by out-and-out socialists, who have done worse to GM than Detroit ever did. Likewise, Vancouver, BC, Montreal, PQ, and Halifax, NS are run by socialists and yet are most pleasant and agreeable places, with safe streets and abundant public services.
Are you sure that you are looking at the right variable?
The reason lot of our large cities are rotting is that the liberals and bleeding hearts have created a large “dependent” class, who are happy to feed at the tax payer’s expense. They do not work hard to acquire marketable skills. Or start a small business and work 16 hours a day like many immigrants do.
Just a few days back I played golf with a person I had never seen before, and he is happy and content to collect his unemployment checks of $550 per week and play lot of golf until the benefit runs out. But at least he had worked for many years before getting laid off. Many people living in the decaying cities have never held a productive job.