Detroit went down because of CROOKED and CORRUPT politicians - people like Kwame Kilpatrick who I am CONVINCED has millions in some off shore account..
Detroit went down because of arrogant corporations, like GM, Chrysler and Ford who all did things they way "they've always been done" and as a result lots billions of dollars.
Detroit went down because the nation's economy collapsed, and Detroit (and the surrounding areas)are just now coming back from that.
It is not because of "liberal policies".
The surrounding area of Detroit is quite healthy. All of the things you are referencing covers the last five years. That's really the only time Detroit's suburban area has been impacted. Detroit itself is a result of 60+ years (not just the last five) of decline.
Nearly that entire time, liberal politicians have run the city council. They have catered to their low income constituents and not their high income tax base. If the city council (liberal politicians and policies) isn't responsible for city financial management, I don't know who is.