That is a necessary but not sufficient condition. There is a reason Democratic dominated places like SF, Seattle and Portland have no risk of going Ferguson.
Oh, they can “go Ferguson.”
Some of the more famous riots/protests in Seattle history
http://blogs.seattletimes.com/today/2012/05/some-of-the-more-famous-riotsprotests-in-seattle-history/
There sure is.
A temporary (historically) stable system with a tax base consisting of very large businesses generating more revenue than can possibly be used wisely, and passing the "costs" on to the country at large. Invisible permanent "wealth."
Watch these government enablers move out of town and the system will collapse. As long as ignorant criminal dysfunctional classes are in charge, it's just a matter of when.