A race riot might be a very foolish thing indeed, at least in the typical places riots happen, like South Central LA. After the Rodney King riot, all patience was lost, both by the police and especially by the Korean community.
In the former case, the police will likely try to arrest all rioters. And if the rioters even enter the Korean community they will be shot.
More likely, riots will be in cities that have not experienced a riot in a long time, like Boston, Indianapolis, Detroit, possibly New York City. Yet even there, I do not expect much tolerance from law enforcement.
And if there are indications or threats of rioting before election day, the police will be very prepared.
The Urban Barbarians have been pushed further and further out from Manhattan over the past 15-20 years, all the way to eastern Brooklyn, south Queens, and the central and eastern Bronx. Many have moved south.
Any rioting would be in a small area, and the NYPD currently has the manpower to deal with it. Hopefully, however, they will do better than the 1964 Harlem riots, when the cops lined up in a baton charge down Lenox Avenue, causing the rioters to simply scatter to the side streets.