Rioters tend to riot in their own backyards unless the riot is the result of an organized/formal protest gone awry or something that breaks out at an event like a sporting event. Why? Because if you're going to destroy and steal property, you do it where you think you won't get caught - in your area (and because of simple logistics). A rioter in Beverly Hills or the Hamptons is going to get busted and locked away. Typically speaking hundreds of people don't collectivity decide in the heat of the moment to get in their cars (or take transit), travel across town, get out of their cars (or off transit) and start rioting.
That being said, I don't think you have to worry. I think Obama is going to take it. It's not a sure thing, but McCain would have to pull off essentially the greatest US election upset in history. I could be wrong, and if I am, you can quote me this thread
