I remember Nixon standing on the hood of a car and, facing a lot of demonstrators, flashing them the V for victory sign. Their reactions and riots helped insure his election. 
For the record, I was one of the protestors and protested pretty much everything that miserable man did. He and Kissinger told the South Vietnamese government not to agree to peace terms, until he got in to office. That war lasted years longer and thousands of more Americans died.
The only way Donald Trump gets to sit in the White House is for many riots to break out. That will bring out a lot of people who perhaps wouldn't have voted for him. Peaceful protest is one thing, overturning cars and hurting people quite another. 
Hugh Massengill, Eugene