We show that contemporary difference in political attitudes across counties in the American South in part trace their origins to slavery's prevelance more than 150 years ago. Whites who currently live in Southern counties that had high shares of slaves in 1860 are more likely to identify as a Republican, oppose affirmative action policies, and express racial resentment and colder feelings toward blacks. These results cannot be explained by existing theories, including the theory of contemporary racial threat. To explain these results, we offer evidence for a new theory involving the historical persistence of racial attitudes. We argue that, following the Civil War, Southern whites faced incentives to reinforce existing racist norms and institution to maintain political and economic control over the newly free African-American Population. This amplified local difference in racially conservative political attitudes, which in turn have been passed down locally across generations. Our results challenge the interpretation of a vast literature on racial attitudes in the American South. Work with Avidit Acharya and Matthew Blackwell.