Hundreds of protesters gathered at the venue at the University of Illinois at Chicago hours before DonaldTrump was due.
Inside the auditorium, fighting broke out between supporters and protesters, who waved flags and chanted.
A statement from Donald Trump’s campaign said the candidate decided to postpone the event after meeting with police.
However, a Chicago Police Department spokesman said the force had not recommended that Donald Trump postpone the rally.
The clashes began more than an hour before the event was due to start, and continued after it was cancelled, minutes after Donald Trump was to have appeared.
There were chants for Donald Trump from his supporters and for Democratic candidate Bernie Sanders from some of the protesters.
There were several violent clashes sparked by Donald Trump supporters attempting to wrestle flags from protesters.
One protester had to be physically removed from the stage by what appeared to be a Secret Service agent.
Violent clashes continued outside the venue, with helicopter footage showing chaotic scenes as police attempted to control the large crowds.
The full statement from Donald Trump’s campaign read: “Mr. Trump just arrived in Chicago and after meeting with law enforcement has determined that for the safety of all of the tens of thousands of people that have gathered in and around the arena, tonight’s rally will be postponed to another date.
“Thank you very much for your attendance and please go in peace.”
Speaking to Fox News after the events, Donald Trump denied using hate speech or playing any part in fostering division.
“I represent a large group of people that have a lot of anger,” he said.
“There is tremendous anger out there on both sides.”
Discussing the decision to cancel the rally, Donald Trump said: “I think it was a very good thing we did, I think it was an intelligent decision.”
Donald Trump’s rivals for the Republican nomination, Marco Rubio and Ted Cruz, both called the incident “sad”.
Sydney has welcomed 2025 with a spectacular fireworks display - cheers erupted as the clock struck midnight…
Following an eight-year legal battle, Angelina Jolie and Brad Pitt have reached a divorce settlement,…
Former President Jimmy Carter died on December 29 at the age of 100 after spending several…
Georgia’s outgoing president Salome Zourabichvili refused to step down on December 29, saying she was…
The bald eagle has been officially declared the national bird of the United States, after…
Dozens of passengers have survived a crash involving a plane carrying 69 people in Kazakhstan,…