The Ku Klux Klan (KKK) had a lasting impact on the number of US Republican voters, even half a century after the white supremacist movement’s popularity and political impact peaked, according to a new study from academics at Yale, Brandeis, and Notre Dame universities.

Professors David Cunningham, Rory McVeigh, and Justin Farrell cite data from five presidential votes between 1960 and 2000 in the paper, published in the December issue of the American Sociological Review. Brandeis reported that it shows that KKK activity “played a significant role in shifting voters’ political party allegiance in the South in the 1960s — from Democratic to Republican — and it continued to influence voters’ activities 40 years later.”

The paper argues that supporters of radical social movements, such as the KKK, are more likely to vote or agree with the political agendas of mainstream parties that appear to share some — but not all — of the extremist views.