It is somewhat unfair to link the riots to larger trends. Smaller communities don't have enough people to riot. Riots are largely an urban problem and big cities rarely ever get Republican Mayors. New York City is an exception to that rule. In general it was lucky to have the professionally run NYPD.
The real cause of riots is long protracted unemployment. The Obama years have been tough on the poor as Obama opened the floodgates to illegal aliens and made Employment Authorization cards a joke. The tax policies in Baltimore made matters worse.
However, one would be hard pressed to think similar riots could not happen in any large city. Sadly, I wish the notion of let the rioters tire themselves out needs to stop.