A KKK march in Harlem would be seriously contentious.
Most Orange marches are not.
A handful out of thousands.
The riots in Belfast were mostly sustained by activists bussed in by RIRA and school kids.

Assistant Chief Constable Duncan McCausland said: "This was a substantially smaller group of people than previous evenings, which included a hardened core of around 12 people who were intent on causing disorder.
http://www.irishtimes.com/newspaper/breaking/2010/0715/breaking17.html