I lived just outside Detroit, now I live in a very rural and conservative community that would have no problem barricading the roads with volunteer militia to keep troublemakers out.
Either place I will be standing with my neighbors, just now I would not be outnumbered 4-1. :^)
However I don't think an Obama loss would cause riots. The average temperature in Nov. in Detroit is probably 45. Has there ever been a winter race-riot? Not that I am aware of.