Résumé : Do mass mobilizations bring about social change? This paper investigates the impact of the Black Lives Matter protests that erupted after George Floyd’s death on the 2020 presidential election. Using local precipitation as an exogenous source of protest variation, we document a marked shift in support for the Democratic candidate in counties that experienced more protesting activity. We use a spatial two-stage least squares estimator, and show that conventional TSLS estimators overestimate the effect size by a factor three. Ancillary analyses show that the effect cannot be explained by changes in turnout. Instead, protests shifted people’s attitudes about racial disparities.