Tens of thousands of anti-racism protesters have converged on the "Free Speech Rally" in the US city of Boston that featured right-wing speakers.
The rally on Boston Common, which attracted only a small crowd, disbanded early and the participants were escorted out by police.
Organisers had said they would not give a platform to racism or bigotry.
Tensions are high after violent demonstrations in Charlottesville, Virginia last weekend turned deadly.
The Boston Herald reported that up to 30,000 people attended the counter-protest. Demonstrators had gathered at a Boston sports centre and then marched en masse to the common.
The BBC's Aleem Maqbool at the scene said those who turned up for the conservative rally were confined to the bandstand area on Boston Common.
Crowds of anti-racism protesters totally surrounded the bandstand but were kept some distance away by barriers, he added.
Many wore stickers with the face of 32-year-old Heather Heyer, who died when a car was driven into a crowd of counter-protesters at last Saturday's far-right rally in Charlottesville.
"It's time to do something. We are out here to add an extra body to the numbers of those who resist," said Katie Zipps, who travelled from Malden, north of Boston, for the counter-protest.
The crowd chanted "No Nazis, no KKK, no fascists in the USA!" and carried banners with slogans such as "Stop pretending your racism is patriotism".
There was a large police presence throughout but no violence was reported.
Speaking earlier, the city police commissioner said he had never seen so many people "almost looking for confrontation".
"I just think the rhetoric has really brought this to a different level," Commissioner William Evans told a news conference on Friday.
The organisers of the "Free Speech Rally" said that "misinformation in the media" was "likening our organisation to those that ran the Charlottesville rally".
"While we maintain that every individual is entitled to their freedom of speech and defend that basic human right, we will not be offering our platform to racism or bigotry," the group wrote on a Facebook page dedicated to the event. "We denounce the politics of supremacy and violence."
The list of speakers for the free speech event changed a number of times in previous days. At times it included speakers who have been associated with the far-right.
The violence in Charlottesville began with a protest and counter-protest over the planned removal of a statue of Confederate commander General Robert E Lee.
In the aftermath, Confederate statues across America have come under renewed scrutiny.
Duke University in North Carolina removed a statue of Robert E Lee from its chapel entrance in the early hours of Saturday morning, following vandalism earlier in the week.
University President Vincent Price said the decision was made for safety reasons and "above all to express the deep and abiding values of our university."