Who can remember all the way back to who punched whom in 2016? From the New York Times news section:

By NIRAJ CHOKSHI MARCH 16, 2018

A study published on Friday appears to confirm what news reports suggested long ago: President Trump’s campaign rallies were associated with a rise in violence when they came to town.

A city that hosted a Trump rally saw an average of 2.3 more assaults reported on the day of the event than on a typical day, according to the study, led by researchers at the University of Pennsylvania and published in the journal Epidemiology. The authors found no corresponding link between assaults and rallies for Mr. Trump’s Democratic rival, Hillary Clinton.

“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.

It may come as little surprise that the rallies were associated with increased violence, as the often volcanic clashes between Mr. Trump’s supporters and opponents were widely covered at the time.

In March 2016 alone, a Trump rally in Chicago was called off after violent clashes broke out, while an anti-Trump protester was punched at a rally in North Carolina and another was punched and kicked at a rally in Arizona. The following month, several Trump supporters were assaulted at a California rally. …

The supporters also often aimed offensive and violent rhetoric at Mrs. Clinton, suggesting she be killed. …

The researchers offered two explanations for the increase in assaults. Either they were the result of clashes at or near the rallies, or they occurred elsewhere in the cities after the aggressive mood on display by Mr. Trump, his supporters or his opponents had spread through “social contagion.”