click to enlarge Lee V. Gaines

Protesters calling for the resignation of Chicago Mayor Rahm Emanuel and Cook County State’s Attorney Anita Alvarez rally during a walk-out march that began as a fake event on Facebook.

Rachel Brown was sitting in her New York University dorm room last week when she decided to make a Facebook event for a party —a resignation party for Chicago mayor Rahm Emanuel and Cook County state's attorney Anita Alvarez. It was a joke, she said.What began as a Facebook invite for a fake event evolved into very real protest in downtown Chicago Wednesday, with hundreds of demonstrators calling for the city's top elected official and the county's top prosecutor to resign. The hours-long march halted traffic, as helicopter blades whirred overhead and dozens of police officers equipped with wooden batons surrounded the moving mass of protesters. An Albany Park native, 18-year-old Brown said she's angry about the shooting death of 17-year-old Laquan McDonald by Chicago police officer Jason Van Dyke, and the way both Alvarez and Emanuel handled the case. But she said she was also upset by the 2013 closure of 50 public schools, and Emanuel's efforts to bring charter schools to Chicago."I think he's trash," Brown says. "He needs to stop being mayor."But Brown says she never expected her virtual resignation party to "become a physical thing," adding that making fake Facebook events and memes are a humorous pastime for her.At most, "I thought maybe [Emanuel and Alvarez] would see it and say, 'Huh, maybe we should resign,'" Brown says.But when Chicago musician David Beltran received the Facebook invitation, his instinct was the opposite: he wanted to turn the fake party into a real protest."I messaged [Brown] and said, 'What do you think about making this real?'" Beltran recounts. "She said she'd make me an [event] admin and put me in touch with a few people."Beltran, 31, said he and Brown have mutual friends in the local music scene but don't know each other personally.Rousemary Vega, a 35-year-old Humboldt Park resident who has previously protested Chicago school closures , volunteered to become an admin on the event page after Brown asked if anyone else wanted to get involved. (Vega says she doesn't personally know Brown either.)As of Tuesday night, more than 1,700 people had RSVPed on Facebook indicating they'd attend the walkout and protest the following day.Beltran says he's not surprised the fake resignation party culminated in a well-attended show of civil disobedience. A musician and cofounder of the local label FeelTripRecords , Beltran was one of the artists behind a mural and shrine dedicated to Chicago Bulls star Derrick Rose's injured knee. The mural appeared in March beneath an I-90 underpass and garnered wide attention after coverage from ESPN, SBNation, and other national media outlets."I know how quickly things can go viral, and I know there's a fine line between memes and joking and actually getting people's attention," Beltran says.For the protest to gain traction and become something more than an online joke, it needed good intentions and good timing, he adds.Beltran remembers taking part in a protest in Chicago in March 2003, a little less than a year before Mark Zuckerberg and his Harvard roommates founded Facebook. Still in high school, Beltran was one of more than 15,000 protesters who marched on Lake Shore Drive to peacefully demonstrate against the U.S. invasion of Iraq. More than 800 people were arrested during that demonstration.The organizers of the 2003 march managed to galvanize huge swaths of people without the help of social media, "which makes you think of the potential of what it can be with the Internet," Beltran says.Three and a half hours after Wednesday's protest began, Vega says she called Brown, who is still in New York City, to thank her for creating the event."She was saying, 'No, I did nothing, you guys put it together,'" Vega says. "I said, 'You initiated it.'"When reached by phone Wednesday afternoon, Brown, a graduate of Whitney Young Magnet High School, was in her dorm room. She said she was "super stoked" by the turnout for the protest.Like Beltran, she also believes in the power of social media and its usefulness as a tool to affect positive change, while also acknowledging the limitations of virtual activism."I don't think it's the end all," she said, referring to social media. "You still need coming together like people did today, but I think it's a really good basis for sharing important information about activism."