Between 1964 and 1971, more than 750 riots flared up in black neighborhoods across the United States. Scholarship on how the American polity respond to these violent protests is contested. Some scholars argue that urban riots produced a conservative ``backlash'' among white voters, while other scholars find little or no effect.  Using a measure that incorporates the location, timing and severity of urban riots between 1964 and 1971, I examine whether increased exposure to urban riots is associated with decreased support for the Democratic party. In the 1964, 1968 and 1972 presidential elections, I find a strong negative relationship between exposure to civil unrest and the county-level Democratic vote share. I find a similar negative relationship between exposure to riots and Democratic vote share in congressional elections between 1968 and 1972. Finally, I find that in counterfactual scenarios of fewer riots the Democratic presidential nominee, Hubert Humphrey, would have beaten the Republican nominee, Richard Nixon, in the 1968 election. As African Americans were strongly identified with the Democratic party in this time period, my results suggest that, in at least some contexts, political violence by a minority group may contribute to a backlash among segments of the mass electorate and encourage outcomes directly at odds with the preferences of the protestors.