"They listed Juggalos as equals alongside highly dangerous and elaborate international criminal organizations like the Crips, the Bloods and MS-13," said Kevin Gill, a Juggalo and podcast host who kicked off the rally.
"As the years have gone by, the effects of this gang report have become very apparent and very, very shocking," he added, saying Juggalos have been profiled by law enforcement, discharged from the military and fired from their jobs for being fans of the band.
Hundreds of Juggalos gathered on the National Mall for the march, which was preceded by speeches from Juggalos who said they've been discriminated against for their support of the band, and performances from musicians on the hip-hop group's Psychopathic Records label.
Brittany Penix, a 26-year-old Juggalo from Indiana, said she came "to prove we are not a gang."
"We support music that has changed some of our lives," she said.
Penix became a fan of Insane Clown Posse when she was 12 and said she used to hide it because she was bullied. "We're tired of being put down," she said.
Scott Young, another Indiana Juggalo, said he's been pulled over because of the "hatchetman" stickers on his car. Hatchetman is a Juggalo symbol showing the silhouette of a man holding a hatchet, and it's popular on shirts and as tattoos.
Juggalos on Saturday stressed their focus on community, chanting "fa-mi-ly" throughout the march and arguing the gang designation is at odds with their inclusive culture.
"If this happens to Juggalos ... then what the f--- happens to us next?" said Violent J, one half of Insane Clown Posse. "What happens to Jimmy Buffet's Parrotheads? What happens to Justin b---- boy Bieber's Beliebers?"
Protesters held signs with phrases like, "I'm a Juggalo not a thuggalo" and "Faygo not fascism," referring to the Detroit soda brand Faygo that's popular with Juggalos.
Juggalos were classified
as a "loosely organized hybrid gang" in the FBI's 2011 National Gang Threat Assessment.
The report said "most crimes committed by Juggalos are sporadic, disorganized, individualistic, and often involve simple assault, personal drug use and possession, petty theft and vandalism."
In 2014, the band and four fans sued the FBI over the classification.
"Juggalos are a 'family' of people who love and help one another, enjoy one another's company, and bond over the music and a philosophy of life," the lawsuit said. "Organized crime is by no means part of the Juggalo culture."
The Metropolitan Police Department closed several roads around the Mall because of Saturday's events, which included supporters of President Donald Trump also taking to the National Mall for what they dubbed the "Mother of All Rallies."
That event aimed to "demand protection for traditional American culture while they express their love for the United States and the America First agenda," according to the group's website.
In a moment that at first seemed it could spark a confrontation, a small group of Black Lives Matter protesters approached the stage, prompting one of Trump supporters speaking on the stage to invite them up and hand them the microphone so they could provide their perspective.
Afterward, the Black Lives Matters protesters left the stage peacefully, without any violence resulting from what wound up being a peaceful day overall.
The organizers of the pro-Trump rally had said that was their goal -- to speak in favor of the President amicably, without a hint of the hatred and violence that gripped Charlottesville, Virginia, last month when white supremacists marched in protest of the removal of a statue of Confederate Gen. Robert E. Lee from a city park.