This historical analysis shows that the 'riot habit' is deeply set in America's political heritage, largely because groups and even classes of citizens have had legitimate grievances and political aspirations which were too frequently ignored by public leaders. Collective violence by such citizens has been one of the few approaches that has consistently forced city leaders to amend their priorities so that citizen grievances could be heard. As distasteful as mass rioting may be to the majority of Americans, a policy to interfere with the political process to discourage mob violence would have even worse consequences for the Nation's cities. It would encourage some minority citizens to abandon any pretense of working with unconventional but largely nonviolent strategies and compel them to undertake a systematic program of urban terrorism in an effort to achieve their goals. The history of mob action in New York City shows that intermittent acts of collective violence occur when established grievance procedures fail. The mob action can force public leaders to make grievance procedures more available and effective. Should officials aim only at repressing civil disorders, the Nation's cities are likely to witness the rise in terrorism that the Nation has so far avoided because citizens have been able to use mob violence so successfully in the past. Seven footnotes are listed. (Author summary modified)