ATLANTA — The white nationalist and provocateur Richard Spencer had left the University of Florida on Oct. 19 when the day’s most serious trouble erupted just beyond the campus.
Three of Mr. Spencer’s disciples from Texas pulled up in a car alongside a group of anti-Spencer demonstrators, and soon, the police said, one of the three began to chant “Heil Hitler.” After a protester hit the car with a baton, one of the Texas men pulled out a handgun and fired a shot.
No one was injured, but the episode underscored a reality of the alt-right movement: that it draws energy, and some of its most violent support, from out-of-town sympathizers who regularly travel hundreds of miles to public events starring figures like Mr. Spencer.
The roadshow aspect of these events — two of which were scheduled to take place on Saturday in Tennessee — makes it hard to determine just how broad the movement is. It also challenges the law enforcement officials who must police rancorous rallies filled with unfamiliar faces from far away.
“The movement has fundamentally changed, since people want to come to these to meet others, to feel a part of the team, so to speak, and to also demonstrate to the outside world that this a real movement and that we want a place at the table,” Mr. Spencer said in an interview on Friday. “Activism is not purely the domain of the left.”
Some demonstrators travel alone, and others car-pool with people from their regions in pickup trucks and rented vans. They stay in motel rooms, often far enough from the events to avoid detection, or on campgrounds after trading suggestions on Facebook, Gab and Twitter.
Alt-right supporters headed on Saturday to two “White Lives Matter” rallies in Shelbyville and Murfreesboro, in Central Tennessee. Organizers chose the region to protest the resettlement of refugees in the area, and to call attention to the shooting last month at a predominantly white church that killed one person and injured several others. The man jailed in the shooting, who is black, left a note that referred to Dylann S. Roof, the white supremacist who murdered nine black churchgoers in Charleston, S.C., in 2015.
In preparation for the rallies, Occidental Dissent, a website popular among white nationalists, offered recommendations and guidelines on topics including attire (white or black polo shirts and khakis “to make a good impression”) and chants (“Blood and Soil!”), as well as a preview of a private event described as “a time to relax, socialize and enjoy the companionship of like-minded people in our movement after two hours of pro-White activism.”
On Friday, about 20 demonstrators, including Harry Hughes from Arizona, had dinner together at an Olive Garden.
“I come to these events routinely because I think we have a message, and we also look for reaction from the public,” said Mr. Hughes, a member of a neo-Nazi group, adding that he often includes sightseeing on his trips.
Zaine Deal, a Traditional Workers Party member from Ohio who was making a quicker trip to the South, said he and 10 other men had driven to Tennessee on Friday for the weekend’s events and planned to leave on Sunday. They split two hotel rooms.
“We’re guys,” a helmet-wearing Mr. Deal, 18, said at the Shelbyville rally on Saturday. “We’re usually arguing about who gets to sleep on the floor.”
Mr. Deal said he planned to travel for more events to advance the same strains of ideology that apparently led the three men from Texas this month to Florida, where they remained jailed on bonds of at least $ 1 million each.
The Texas men had growing histories as activists who were willing to travel from their homes in the Houston area to support the alt-right, and all three attended the “Unite the Right” rally in Charlottesville, Va., that turned deadly when, according to the police, a white nationalist from Ohio drove his car into a crowd. One of the men arrested in Florida, William H. Fears, had also surfaced at other events, including at least three in Texas, according to news and social media accounts of the events.
A few hours before the shooting, Mr. Fears, who faces a charge of attempted homicide, spoke to The Gainesville Sun about what he depicted as the movement’s newfound aggression.
“We’re starting to push back, we’re starting to want to intimidate back,” he told the newspaper. “We want to show our teeth a little bit because, you know, we’re not to be taken lightly. We don’t want violence, we don’t want harm, but at the end of the day, we’re not opposed to defending ourselves.”
On Friday, asked about the charges against Mr. Fears and the other men, Mr. Spencer said: “If the allegations are correct, then they really did a bad thing. It’s not defensible, to be honest.”
But Mr. Spencer and his allies have no plans to abandon the events that prompt controversy and turmoil. Brad Griffin, the publisher of Occidental Dissent, estimated that up to 90 percent of people at the alt-right’s public events are regulars who travel from afar, a figure Mr. Spencer agreed with. Mr. Griffin said that the movement struggled to attract more local support because of the promise of public condemnation.
“We’re breaking a taboo,” said Mr. Griffin, who also oversees public relations for the League of the South, which describes itself as a “Southern nationalist” organization, and who helped promote Saturday’s rallies. “We might have supporters in the area, we might have supporters in the state, but the number of people who are willing to take those risks always reduces turnout.”
The movement’s most fervent activists are often met by left-wing opponents, like those in the Antifa movement, who have a similar, if more extensive, history of traveling. They normally benefit, observers said, from long-established networks that support liberal protesters, sometimes offering meals and couches to crash on.
Starting with the street clashes in Seattle during the World Trade Organization conference in 1999, “you just see this roving band that was at everything,” said Scott Crow, a longtime liberal activist and author who lives in Texas. “You’re probably not seeing the same Antifa people at every Richard Spencer rally, but there are people who are probably at many of those things or the big ones.”
Federal officials have long paid close attention to activists all along the political spectrum, sometimes infiltrating groups they consider extreme. Yet traveling demonstrators, no matter their ideological alignment, often pose particular challenges for the local authorities, who may have little experience handling volatile protests and limited knowledge about people who come from afar.
Social media platforms and the internet only add to the challenge, experts said. While technology yields greater opportunities for intelligence gathering, it also allows for greater coordination among some extremists who, until recently, would have probably stayed close to home.
“They were geographically isolated, they would interact with others and, on occasion, they would travel,” said John D. Cohen, a former acting undersecretary for intelligence and analysis at the Department of Homeland Security. “What’s different today than, say, five years ago is that more and more people seem to be self-connecting with the cause of white supremacy versus joining a white supremacist group.”
And experts said a blend of easy access and coordination, as well as perceptions of a hands-off approach to policing past rallies, sometimes draws outspoken activists who ordinarily would have remained “underground.”
On the web page with instructions and guidelines for the demonstrations in Tennessee, Mr. Griffin included an admonishment that “another Charlottesville” is “not in our interest.” Rather, one of the weekend’s stated objectives was to “foster greater unity and cohesion within our own movement.”
Mr. Griffin, despite his movement’s record of failing to attract many local supporters, said he was hoping Tennesseans would be more open to their beliefs than Charlottesville residents were.
But in Shelbyville, outside the small area designated for the demonstrators, the streets seemed to be dotted only by police officers, journalists and counter-demonstrators. Mr. Deal, the helmeted Traditional Workers Party member, surveyed the crowd and pointed at his political opponents.
“These guys are just like us,” he said. “None of them are from around here.”