White-flight from most of our major metropolitan areas since WWII shouldn't be news to anyone. And that the population who has replaced them has mainly voted democrat, I don't see that as the cause of anything. You could also overlay any number of other socio-economic stats such as income, education level, crime, etc.

Mayors can't do much with their budget if the tax-base disappears -- doesn't matter if they are the staunchest conservative or biggest bleeding-heart liberal. Sure -- there has been plenty of goofball democrat mayors that made some poor decisions, but in the grand scheme of things --- these inner cities are not poor because of who they elected as mayor. Thats ridiculous.