King's College London

Researchers Dr Bouke Klein Teeselink, of King's College London, and Dr Georgios Melios, of the London School of Economics and Political Science and Royal Holloway, University of London, found that counties with BLM protests experienced a 1.2-1.8 percentage point increase in Democratic vote share compared to similar counties without protests.

"Given how close the election was in key battleground states, our findings suggest that the BLM movement may have played a decisive role in determining the election outcome," said Dr Klein Teeselink, a Lecturer in Philosophy, Politics, and Economics at King’s. "This represents one of the most consequential impacts of a social movement on electoral politics in recent history."

The study, titled ‘Weather to Protest: The Effect of Black Lives Matter Protests on the 2020 Presidential Election’, employs innovative methodological approaches to establish a causal relationship between protests and voting behaviour.

The research reveals that BLM protests initially triggered a conservative backlash, increasing support for Republican candidates in the immediate aftermath. The authors said this might have been due to the media’s focus on the more violent aspects of the protests. Over time, however, as violent imagery faded from public discourse, the backlash reversed and turned into a progressive shift in voting behaviour. Moreover, protests didn't just mobilise existing Democratic voters – they substantively shifted people’s beliefs about racial inequality.

"What makes these findings particularly interesting is the temporal dynamic," said Dr Melios, a Research Fellow at LSE. "Our research helps explain why previous studies on protest movements have shown mixed results. The timing between protests and elections matters tremendously for determining whether demonstrations help or harm their cause."

The study also offers insights for current social movements, suggesting that collective action can meaningfully reshape political preferences, though success depends on timing relative to elections, media framing, and, plausibly, protest tactics (violent versus non-violent).

This research contributes to ongoing debates about the effectiveness of mass mobilisations in driving social change and offers empirical evidence that one of the largest protest movements in US history substantively influenced both electoral outcomes and attitudes about racial justice.