A new study finds a correlation between violence and President Trump Donald John TrumpBiden leads Trump by 36 points nationally among Latinos: poll Trump dismisses climate change role in fires, says Newsom needs to manage forest better Jimmy Kimmel hits Trump for rallies while hosting Emmy Awards MORE's campaign rallies.

The study — led by researchers at the University of Pennsylvania and published in the journal Epidemiology — found that on average 2.3 more assaults were reported in a city on the day it hosted a Trump campaign rally than on a normal day.

“It appeared to be a phenomenon that’s unique to Donald Trump’s rally,” said Christopher Morrison, a postdoctoral fellow at the University of Pennsylvania and the lead author of the study, according to The New York Times.

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President Trump's rallies during his 2016 presidential campaign were often met with protesters and sometimes resulted in violent clashes.

In March 2016, a scheduled Trump rally was canceled in Chicago after clashes between Trump supporters and protesters. During another rally in 2016, a protester was punched and kicked while being removed.

Trump also in the past addressed protesters at his rallies. During a November 2015 rally, he said maybe a protester "should have been roughed up." In November 2016, he said of a protester that he would “like to punch him in the face."

He also said in the past he was looking into paying the legal fees for a man who had allegedly sucker-punched a protester during a rally.

The researchers on the study suggested that the rise in assaults on the days of Trump rallies either came from violence at or near the rallies, or they stemmed from the "aggressive mood" shown by Trump and his supporters and took place at other locations in the cities.

The researchers noted that the increased number of police at Trump rallies could have made it more likely an assault would be reported on those days, as well.