Terrorism is defined as the use of violence and intimidation in the pursuit of political aims. Let us review what has been happening in the United States of late, and we will see if these events fit the definition of terrorism.
On Sunday, October 16, 2016, anti-Trump activists firebombed the North Carolina GOP headquarters, and left a chilling message spray-painted onto the wall of an adjacent building: Nazi Republicans leave town or else. The message also contained the swastika.
On June 2, 2016, anti-Trump protestors hunted down and assaulted attendees at a Donald Trump rally in San Jose. They confiscated 'Make America Great Again' hats and signs from rally attendees, and set fire to these items while also burning American flags. They pelted a woman with eggs while shouting slurs and threats at her as she stood in defiance of them.
May 25th, 2016, in Anaheim, California, police arrested several protestors who attacked Donald Trump rally attendees.
May 24th, 2016, in Albuquerque, New Mexico, protestors threw rocks and bottles at the police in an attempt to breach the line to get to Donald Trump rally attendees. Many police cars were damaged during the attack.
In almost all the Donald Trump rallies near the Mexico border, rally attendees would go home after the rally, many of them with children, and anti-trump protestors would threaten them with violence, saying things like, 'This is our town. We know where you live.'
March 12, 2016, Thomas Dimassimo, a 32 year old man, attempted to attack Donald Trump while Donald Trump was speaking at a rally in Dayton, Ohio. Secret Service stopped Dismassimo, and charged him with misdemeanor and inducing panic.
March 11, 2016, Chicago, protestors stormed the convention centre where a Donald Trump rally was scheduled to take place. The protestors attacked the rally attendees, and attacked the police. Donald Trump was forced to cancel the rally due to concerns that the violence would only get worse.
This is just the tip of the iceberg. In every instance, anti-Trump protestors have used both violence and threats of violence in order to intimidate Donald Trump supporters. The goal of these protestors is obviously political in nature. What they are doing fits the definition of terrorism. Go to Wikipedia and look up the timeline for yourself. Replace every instance of 'protestor' with 'political terrorist' and you will have a more accurate accounting of events.
Although evidence is lacking at this point, I suspect that these violent 'protestors' were paid to get violent. They are professional agitators. If they weren't paid to get violent, and if their actions were truly genuine, then this does not bode well for the future of American politics. So far, the violence has been limited to firebombings of empty buildings, physical assaults, and verbal threats. If the sentiment on the ground is that political violence is justified, then it won't be long before we see people dying for their political beliefs.
Just as a side note, if people truly believe that they are opposing 'literal' Hitler, then I can see why they think violence is justified. Hitler was a bad guy who killed lots of innocent people. Violence against truly evil, mass-murdering maniacs is not a bad thing. Unfortunately for the anti-Trump crowd, Trump is not even close to Hitler. Trump is a business man who builds hotels. On the other hand, Hitler, before he came to power, was already politically active, and had directed terrorist attacks against his political opponents. He attempted a coup. That's why they jailed him in 1924. People who make this comparison need to study history.