Violence on the campaign trail

FOX 5 NEWS - A lot of people watching the violence unfold over the weekend were wondering what is happening to American politics. It is actually not the first time an election sparked physical conflict in the U.S. it happened among Democrats back in 1968. We talked to an author and a political historian who took us a little bit deeper into the accuracy of those comparisons.

On Fox News Sunday Donald Trump defended his campaign against concerns that his last three planned rallies have been plagued by violent outbursts.

The U.S. certainly has a history of violence when it comes to election years. And taken in context the tussles this weekend could be looked at as minor. But Rutgers Professor David Greenberg argues that decades have passed since we've seen this kind of uproar.

Friday night, Trump cancelled an appearance in Chicago when violent protests erupted both inside and outside the rally. That is the same city where protesters and police clashed during the 1968 Democratic convention.

But that was during the height of the Civil Rights movement and the Vietnam War. It was a year was marked by the assassinations of Martin Luther King Jr. and Democratic presidential candidate Robert Kennedy.