Just about any teenager in Chicago today can tell you the story of Chief Keef and Lil JoJo, two rappers from the South Side neighborhood of Englewood whose songs serve as anthems for their rival gangs. Keef, an 18-year-old whose real name is Keith Cozart, is the most successful of the city’s emerging “drill” sound rappers (named after a slang term for shooting someone). Last year, while under house arrest for aiming a gun at a police officer, Cozart uploaded some videos to YouTube that eventually landed him an estimated $6 million deal with Interscope Records. The title of one of his early hits, “3hunna,” is a nickname for the Black Disciples gang, and in the song he maligns the Tooka gang, a crew affiliated with the enemy Gangster Disciples. “Fucka Tooka gang, bitch, I’m 3hunna,” he chants. Last spring, Joseph Coleman, then a baby-faced 18-year-old calling himself Lil JoJo, responded to Chief Keef’s musical provocations with his own uploaded song that included the hook “Niggas claim 300 but we BDK,” that is, Black Disciples Killers. In his “3HUNNAK,” Coleman also threatened to shoot a member of Chief Keef’s clique, and the video—which quickly captured close to a million views on YouTube—consists mostly of a throng of guys jostling into the frame, pointing an arsenal of firearms at the camera. This touched off an online war between the two rappers that lasted for weeks, and young Chicagoans followed in real time as it escalated.

On September 4, 2012, Lil JoJo drove down Black Disciples’ block, a few streets from his own. He posted video footage to his Twitter account in which he shouts profanities at someone he passes who clearly shouts back, “I’ma kill you.” That same afternoon, amid a flurry of broadside taunts fired off on social media by each side, Coleman tweeted, “lmao im on 069 Stop The Fuckin flexin.” A little while later, while riding on the back pegs of a friend’s bicycle, JoJo was shot and killed on the 6900 block of South Princeton Avenue. Soon thereafter, a pair of comments appeared on Chief Keef’s Twitter account:

Keef, who has a mop top of noodling dreadlocks that hang past his eyes shaggy-dog style, said he didn’t write the derisive tweets about JoJo’s murder, claiming his account had been hacked. In an unrelated matter, he ended up serving a short stint in juvenile detention for violating his parole—he was filmed handling a rifle in an online video commissioned by Pitchfork.com. But he continues to Instagram images of himself with guns and drugs, sharing the pictures with his 750,000 Twitter followers, and upon his release from juvie he promptly tweeted, “Fucka TOOKA gang!!! BITCH IM 3Hunna.”

Coleman’s murder sparked a round of back-and-forth retaliation killings—a 26-year-old parolee who appeared in a video mocking JoJo’s death, an 18-year-old in a JoJo sweatshirt on Christmas Day. #BDK and #GDK (Gangster Disciples Killers) became trending terms on Twitter, showing up in thousands of tweets. At Coleman’s funeral, posted to YouTube, hundreds of youths sang in unison the chorus to his online hit: They “claim 300 but we BDK.” The Chicago police fielded calls from departments in four different states, where officers were struggling to understand why people in their jurisdictions were declaring themselves to be warring branches of the Disciples and fighting over some kids from Chicago’s South Side. Even a full year later, the two rappers are cited in countless videos, comments, and posts as shorthand for disrespect or a call to arms.

Last year more than 500 people were murdered in Chicago, a greater number than in far more populous cities such as New York and Los Angeles. The prevalence of gun crimes in Chicago is due in large part to a fragmentation of the gangs on its streets: There are now an estimated 70,000 members in the city, spread out among a mind-boggling 850 cliques, with many of these groupings formed around a couple of street corners or a specific school or park. Young people in these areas are like young people everywhere, using technology to coordinate with their friends and chronicle their every move. But in neighborhoods where shootings are common, the use of online tools has turned hazardous, as gang violence is now openly advertised and instigated online.

We naturally associate criminal activity with secrecy, with conspiracies hatched in alleyways or back rooms. Today, though, foolish as it may be in practice, street gangs have adopted a level of transparency that might impress even the most fervent Silicon Valley futurist. Every day on Facebook and Twitter, on Instagram and YouTube, you can find unabashed teens flashing hand signs, brandishing guns, splaying out drugs and wads of cash. If we live in an era of openness, no segment of the population is more surprisingly open than 21st-century gang members, as they simultaneously document and roil the streets of America’s toughest neighborhoods.

There’s a term sometimes used for a gangbanger who stirs up trouble online: Facebook driller. He rolls out of bed in the morning, rubs his eyes, picks up his phone. Then he gets on Facebook and starts insulting some person he barely knows, someone in a rival crew. It’s so much easier to do online than face-to-face. Soon someone else takes a screenshot of the post and starts passing it around. It’s one thing to get cursed out in front of four or five guys, but online the whole neighborhood can see it—the whole city, even. So the target has to retaliate just to save face. And at that point, the quarrel might be with not just the Facebook driller a few blocks away but also haters 10 miles north or west who responded to the post. What started as a provocation online winds up with someone getting drilled in real life.

In the middle of a weekday this spring, I visit Hal Baskin, a former gang member turned community leader who operates an after-school program called the Peace Center out of a decommissioned church building in Englewood. At the brick two-flat house where he was raised and his mother still lives, two of Baskin’s younger relatives and a couple of their lifelong friends tell me all about Facebook drillers. All in their early twenties, they are hanging out in an adjoining lot, the four of them circled around a stone table with a chessboard painted on it. The house is on Morgan Street, and that’s how they identify themselves, as Morgan Street guys. They grew up together playing in this very yard, throwing rocks and footballs, building a clubhouse at the far end behind the vegetable garden. Like just about everyone in this part of town, they followed each twist of the Chief Keef and Lil JoJo saga. Morgan Street is Gangster Disciple territory, JoJo’s turf, and it becomes clear that these guys’ loyalties follow suit—at least when it comes to music.

“Chief Keef is an ABC rapper, saying little bitty words,” says Deandre, one of the young men. “got a 30,'” he goes on, his deep, raspy voice turned into a mocking drawl. “got a cobra.’ That’s all he can do. He out there just gangbanging.” (A “cobra” is a .357 Magnum, and a “30,” or “30-poppa,” is an easily concealed handgun with a 30-round clip.)

“Every song’s like,”We out here drilling! Aughhh! Aughhh!'” one of Baskin’s relatives says dismissively.

“JoJo was saying things that make you think,” a friend named Novell cuts in.

Their vague association with a centralized gang is in keeping with a fundamental shift in how gangs operate, both here in Chicago and around the country. Harold Pollack, codirector of the University of Chicago Crime Lab, says that in every talk he gives about gangs, someone inevitably asks him about The Wire—wanting to know who is, say, the Stringer Bell of Chicago. But The Wire, based in part on David Simon’s Baltimore crime reporting in the 1980s and ’90s, is now very dated in its depiction of gangs as organized crime syndicates. For one thing, Stringer Bell would never let his underlings advertise their criminal activities, as a Central Florida crew did this spring when it posted on its public Facebook page that two of its members had violated their parole and been arrested for posing with guns on their personal Facebook pages. Even a few years ago, a member of, say, the Disciples would have been “violated”—physically punished—for talking about killings or publicly outing a fellow member. But today most “gangs” are without much hierarchical structure, and many of the cliques are only nominally tied to larger organizations.

Similarly, the majority of the violence isn’t strategic but results instead from petty personal exchanges. Young people in embattled Chicago neighborhoods are scared and heavily armed—police seize more guns than the NYPD and LAPD combined, an average of 130 illegal firearms each week. “A couple of young guys, plus a disagreement, plus guns equals dead body,” Pollack says bluntly. “These are stupid 17-year-old homicides. That’s the extent of it today.”

Increasingly, disagreements that end in bloodshed have their origins online. The Chicago police department, which now patrols social media along with the streets, estimates that an astonishing 80 percent of all school disturbances result from online exchanges. At one point on Morgan Street, a 15-year-old joins us at the stone table. He calls himself Boss Nick, and he says he regularly posts pictures to Instagram of himself with guns. He doesn’t care if the police or his teachers or really anyone sees it. He feels he has to let rivals know he is out there “with these poles.” Boss Nick had been friends with Shondale Gregory, known as Tooka, a 15-year-old killed in 2011. Gregory was shot in the head, and rivals soon posted pictures of his corpse to Facebook, doctoring the image with horns and splattered brains. The Chicago police said that within minutes of the images’ appearing on the site, 81 kids at Gregory’s high school were suspended for fighting and an additional 200 students walked out. Gregory’s clique of Gangster Disciples, which had called itself the St. Lawrence Boys for their block on the South Side, started referring to their turf as Tookaville and to themselves as the Tooka Gang.

“All that ’cause of Facebook,” Baskin’s 20-year-old grandson says. “That’s why Tooka blew up.”

Unlike Boss Nick, the other Morgan Street guys are past the age where they’re most at risk of falling prey to the violence in the neighborhood. Deandre says he’s training to be an auto mechanic, another friend hopes to land a job with the Chicago Transit Authority, and Novell expects he’ll soon start work at a McDonald’s. Most of them sport a preppy look, Polo and Izod caps worn frontward, short-sleeved collared shirts.

Ronald, the quietest of the bunch, is enrolled in barber college. He’s more sparing with his words, though every few minutes he points at my scribbled notes to correct something I’ve gotten wrong—the name of yet another nearby gang faction, the spelling of the next street over.

“If Facebook and all that wasn’t here,” Ronald finally says, “JoJo and them would still have their lives.”

Even for an outsider,the online gangosphere isn’t difficult to enter. Sites like TheHoodUp.com and StreetGangs.com host message boards where gangsters openly swap tips and tricks: how much an ounce of weed is worth, how to bribe a cop or judge. Videos from ChiTownBangn and Gang Bang City Ent. look like the thug-life version of Girls Gone Wild, the cameras inspiring kids to act out vicious caricatures of themselves. WorldStarHipHop.com has become a clearinghouse for amateur fight videos, with guys often shouting “Worldstar!” as they record themselves administering beatings or film someone else being pummeled; the site even puts together best-of-the-week fight compilations.

On YouTube, search for the name of any gang or clique, or better yet the name plus “killa” (“Vice Lord Killa,” “Latin Kings Killa”), and you can quickly find yourself on just about any block in gangland America. In these videos, guys proudly proclaim their allegiance into the camera, shouting out tributes to their gang and even announcing their own names and aliases. People in the videos often light up a joint or flash a gun tucked in their waistband while bragging to the camera that they know the police are watching.

As with the gangs themselves, though, the gangland videos often sit on a blurry line between criminality and sociality. The goal is really to display a strength in numbers and firepower—an image seen by foes a few streets away as well as by the next generation of kids on the block. On YouTube, you’ll find thousands of amateur rap videos that seem to double as gang videos, with rappers giving shout-outs to the various cliques in their neighborhood, their friends stepping into the background—or the foreground—to show off a gun and act crazy. The YouTube video for “WildEnd We Out Here,” a hip hop track by an 18-year-old named Yung Killa, or YK, opens with an anarchic late-night party scene in the city’s legendary Cabrini-Green housing project. As YK name-checks each gang, we see its members joyously throwing up their crooked finger signs.

Not long ago I met up with Yung Killa, whose real name is Devonta Hodge, and Deandra Howell, a 20-year-old who goes by Lil Dre Day. WildEnd refers to both the section of Cabrini-Green where they’re from and their rap collective, WildEnd Entertainment. We speak in my car, parked in the lot of a Pizza Hut along the Dan Ryan Expressway on Chicago’s far South Side. “Social media is going to put you out there, but it’s not all going to be pretty,” Howell says from the passenger seat. And while they self-identify as onetime gangbangers, the two young men insist that their YouTube videos are like crafted “movie skits” and aren’t intended to glorify (let alone provoke) acts of violence. Their current goal is to make it onto MTV or BET’s 106th&Park. But the songs do draw inspiration from their lives in the projects, where gangs and guns and extreme poverty are the everyday reality; just a few months prior, their manager was shot to death as he sat right beside them.

Peering over my shoulder from the backseat, Hodge asks why the name Ryda Gang is written in my notebook. I tell him that I watched a couple of Ryda Gang videos on YouTube. In one of them, a group of young men are parked outside the Cabrini row houses as they film themselves in a black minivan at night. “Curfew time!” someone yells out, as others appear along the narrow strip, Hodge among them. A person from the van announces into the camera that he’s affiliated with the Black Disciples. Another one, describing himself as a gang veteran, zeroes in on the five blue-light surveillance cameras that surround the block, detailing for anyone with an Internet connection his plans to cut the wires on one of them. Apparently he doesn’t like to be watched.

“Ryda Gang is a gang gang,” Hodge says, stressing each word as if willing me to comprehend. “WildEnd is a music group.” But as the fate of Lil JoJo shows, on the Internet especially it’s hard to differentiate between the two. Hodge may have taken at least one lesson from that tragedy. When a minor online kerfuffle seemed to be brewing between Yung Killa and Chief Keef, the WildEnd guys were quick to squash it. Hodge got right in touch with Cozart—by phone.

The headquarters of the Chicago police department is on the South Side, a couple of blocks from where the White Sox play and not far from where the Robert Taylor Homes, once the country’s largest housing project, stood until they were torn down nearly a decade ago. On the day I visit the station, 20 recruits who have just completed their training line up in front of a mural of the neighborhood, preparing to be sworn in for duty. I sit down in a folding chair near Kevin Ryan, commander of the gang enforcement unit, and Ken Boudreau, a 27-year department veteran who runs the gang unit’s school-safety team. Over his protruding belly, Boudreau wears a worn bulletproof vest, its Velcro straps frayed and discolored. On the seat beside him, he places a BlackBerry and a second phone, each emitting constant chirps.

Ryan, in a brown pin-striped suit and trim mustache, takes an iPad from his briefcase. He’s reluctant to talk too specifically about the methods they use to monitor the online activity of gangbangers, for fear of limiting his capabilities. But he assures me that I could figure out most of it just by tooling around with a few search terms. On his iPad, he types “CPDK,” for Chicago Police Department Killers, and shows me the string of results on YouTube, guys crowing in each video about their desire to kill cops.

Gang enforcement officers in Chicago started looking closely at social media sites about three years ago, after learning that high school students were filming fights in the hallways and alcoves of their schools and posting the videos online. Boudreau tells me that they began to hear about fight videos going on YouTube during the day, and then they would often see a related shooting later in the afternoon. In the department’s deployment operations center, the other unit in the force that regularly monitors social media activity, officers first took notice when they read in the newspaper about a West Side gang member who was using the Internet to find out about enemies being released from prison. But “virtual policing” became a priority only after kids aligned with local cliques started calling each other out in rap videos.

Much of this police work is reactive. In the same way that flyers taped to light poles used to announce parties, news of a big gathering is now posted online, and officers move into position based on that intel. Other times guys will say point-blank that they’re going to kill someone. “We’re like, oh shit, we better put some police there because this is about to set off,” an officer in deployment operations says. When people brag about a crime they’ve already committed, detectives use that as yet another investigative tool, assuming that online admissions alone won’t hold up in court. (Though in one successful case, a Cincinnati district attorney was able to introduce thousands of pieces of online evidence of suspects appearing beside guns, drugs, and one another to establish a criminal conspiracy.)

But over time, the cops’ approach to social media has become more entrepreneurial. The police in Chicago now actively look for inflammatory comments around specific dates: the anniversary of a homicide, say, or the birthday of a slain gang member, the sorts of events that have often incited renewed rounds of violence. They also use information collected from public sites to add to their knowledge about the hundreds of cliques and sets operating in the city, cataloging the members, affiliations, beefs, and geographic boundaries.

“We saved a life this week,” Boudreau says. A middle-school student from Englewood had denigrated Chief Keef and the Black Disciples in a rap video. Looking at the comments, Boudreau’s team could see that Keef partisans were mobilizing; the online taunts were close to spilling over into real-world violence. The police notified the 12-year-old’s family, and he and a classmate were relocated from the neighborhood. The next day the police spotted the rivals prowling near the boy’s home. It was the same story as JoJo’s, Boudreau says, except with a different ending.

Police and other experts say the ad hoc, emotional nature of street violence today might actually present an opportunity. Repairing big rifts between warring criminal enterprises is really hard; defusing minor beefs and giving kids skills to regulate their socio-emotional behavior is highly labor-intensive but effective. And the public nature of social media gives police and advocacy groups some warning about trouble before it starts. For a long time, criminal-justice experts have talked about predictive policing—the idea that you can use big data to sniff out crimes before they happen, conjuring up an ethically troublesome future like the one depicted in Steven Spielberg’s Minority Report. But in Chicago and other big cities, police are finding it’s much easier than that. Give people social media and they’ll tell you what they’re about to do.

Just as Chicago cops helped save that 12-year-old in Englewood, police departments around the country are trying to use information gleaned from online posts to anticipate crimes and prevent them from ever taking place. In Cincinnati, officers at the police department’s real-time crime center track dozens of sites daily in a room filled with video monitors. Captain Dan Gerard, who runs the unit, says they want gangbangers to know that the police are watching. A beat cop can bait a suspect who passes on the street: I know you were out celebrating last night; I know who you were with. “It’s designed to get in their heads, to rattle them, so they put the guns down,” Gerard says.

In New York City, where the number of homicides is now the lowest since it started keeping crime statistics 50 years ago, the NYPD credits much of its recent success to monitoring online gang activity. The department determined that street-crew members, by and large teenagers, were responsible for a vastly disproportionate share of the violent crimes in the city. And so last year it launched Operation Crew Cut, which is doubling the number of detectives in its gang division to 300, with many of the additional officers focusing specifically on social media sites. The result, authorities say, has been a steep drop in retaliatory violence, as the police have been able to identify clashes and step in before they escalate. “Any tweet might hold the identities of the next potential victim and perpetrator,” NYPD deputy commissioner Paul Browne says.

There are some signs in Chicago too that police and community efforts might be working. Compared with its pace in 2012, the homicide rate this year has decreased. But as of mid-August, there were still more than 220 people murdered and 1,000 shot; 47 shootings occurred over the July 4 holiday weekend alone. The daily scorekeeping itself has turned into a grim yardstick, a gauge of the quality of life in a place where life is valued far too cheaply.

For kids stuck in these areas wracked by shoot-outs, the best defense is learning how to minimize risk, both online and off. Most of them just want to appear hardened, tough, but not so tough that they stand out; the goal is a level of invisibility that makes them a less likely target. Jason Story, a former gang member from the South Side, is now one of several teachers in a Chicago-wide program called BAM (short for Becoming a Man), a 30-week class aimed at 1,500 troubled high school freshmen and sophomores. He feels that by focusing on issues of integrity, self-determination, and positive anger expression, BAM is steering many of these wayward teens away from dangerous activities on social media and the streets.

Beyond that, simply living in the neighborhoods teaches young people new ways to behave online. The Morgan Street guys tell me some of the basic rules for Facebook. First, don’t make friend requests to rivals or accept any from guys you don’t know. Second, borrow someone else’s phone when possible—ideally a girl’s—to browse the site. But third, don’t quit social media entirely: You need to know who is cliqued up with whom, who is making threats, who might try to catch you unawares. Novell’s route to the McDonald’s will take him right past Black Disciples territory. The Morgan Street guys point beyond the garden where they played as children to the multiple vacant lots and spaces between the neighboring properties. Do I see all those “side cuts”? Some 14-year-old with a gun could emerge at any time from any one of them, they say.

Before I leave the Baskin family home, Novell says, “I ain’t going to lie. On my Facebook page, I’m on there showing my guns off. It’s how you advertise yourself.” It doesn’t matter that he makes himself a target for the police, that cops sometimes stop him to say, “I see you got a new gun. Where’s it at?”

The way he sees it, he is both endangering his life and protecting it. He feels he has to let the BDs know he has big guns just like theirs. It’s an arms race, escalated by the projections of power made on the web every day. “I’m my own police,” Novell declares. “Someone says something to me on Facebook, I don’t even write a word. The only thing I do is post my 30-popper, my big banger.”

It was only a few days later when, back home, I saw the news headline out of Chicago. In the late afternoon on Mother’s Day, Ronald — the quiet one, the one who hoped to be a barber — and Hal Baskin’s grandson were pulling away from the house on Morgan Street when someone stepped from a building and fired on their car. The grandson ducked and scrambled to the street. Ronald was hit in the neck and killed. Some of the news outlets ran a picture of Ronald grabbed from his Facebook page. He’d tried hard to look stern as he took it, holding up his smartphone, snapping the self-portrait in his bathroom mirror.

Ben Austen (@ben_austen) wrote about the legacy of Steve Jobs in issue 20.08.