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.

Due to a lack of knowledge of the details of a politician's voting platform, one apparently unifying belief can lead voters to embrace a political party with which they might otherwise have little else in common, according to the report. Over time, the desire of family, friends, and the community to homogenize their views can work to reinforce the status quo.

This does not mean that the KKK is currently flourishing — many reports show that recent recruitment drives are more a sign of dwindling support than continued influence.

"The paper does not suggest in any way that KKK members continue to be influential in Republican politics," McVeigh, one of the study's authors, told VICE News. "The article instead reveals that the Klan's presence in southern communities did have an effect on voting outcomes in the 1960s and that historical effect has endured over time."

The study also talks about factors such as "dissonance reduction," when human beings avoid conflict, and "takeoff issues," when an issue reaches such a high status in the public eye that it breaks down social barriers and becomes widely discussed, overriding people's habit of "dissonance reduction."

The academics claim that when a "takeoff issue," such as race (or race as highlighted by the violent tactics of the KKK), overcomes a community's desire for dissonance reduction, it leads to the "restructuring of social relationships" and a community's political allegiances and views.

A large part of the paper, McVeigh explained, is oriented toward explaining "how it is that past voting behaviors can become 'locked in' in the aftermath of a major change or disruption of the status quo."

Mark Potok, director of publications and information at the Southern Poverty Law Center, a non-profit organization that works to counter extremism and hate crimes, told VICE News that the voting trends in the American South were counterintuitive.

"Polarizing extremists as a general matter really do have lasting impact on the communities," Potok said. "They cause people to vote against their own self-interest, which is what happened [with the KKK] in the South, with people, especially the working people, voting for a party that favors wealthier people and big business."

Even in the "information era" of internet and social media, radical influences can have a much longer lifespan than the movements that spawned them.

"There is a lot about social media that can simply reinforce a world view," McVeigh said. "We still tend to interact with people who are most similar to ourselves and we can choose to get our news from outlets that present the news in ways that are consistent with our own worldview. Progressives, for example, may watch MSNBC and conservatives may watch Fox News."

While the study looks at the resonating effect of the KKK's historic influence, Potok says the research backs up a number of more general principles he has found in his own work.

"We found over the years that extremist rhetoric when it is helped into the mainstream by enablers has a very profound effect," Potok said. "When [Newt] Gingrich compared Muslims to Nazis in 2010 it was not a surprise to see a few months later that the number of hate crimes against Muslims went up and led to the passage of ridiculous anti-Sharia laws in many states."

The KKK study, published amid widespread protests across the US over police abuses and the killings of unarmed African-American men in Ferguson, Missouri, and New York, looks not at protests but the consequences of radical movements.

The KKK had a resurgence after the civil rights efforts of the 1950 and 60s, but McVeigh thinks it's unlikely that a similar sort of reaction could occur today, although VICE News recently reported that a KKK group was fundraising for Darren Wilson, the Ferguson policeman who shot Michael Brown.

"Many may find the protests to be objectionable, but the protests are not threatening to their interests in the same way that civil rights action in the 1960s threatened the interests of white southerners," McVeigh said.

Five decades after the civil rights movement, however, black and white Americans tend to have very different views about race.

"This is related to high levels of residential segregation that persist in American society that can lead to very different types of interactions that people have with the police and different evaluations of what kinds of police action are justifiable," McVeigh added.

Potok believes that the protests springing from the deaths in Ferguson and Staten Island could grow into a national movement and, as a result, also highlight what he believes is an increase in right-wing Republican sentiment as a reaction to the prediction that white people will become a minority in the US by 2043.

"I think the main thing that is happening is that whites are beginning to react in very large numbers to an imminent loss in their majority which is driving a lot of the Republican movement and giving rise to the anti-immigration movement," Potok said.

"Ferguson and Staten Island have added to the fire but a real fury is developing among the white electorate. Black people should quit complaining and shut up — that seems to be message from the right."