“Most of our violence is gang related, much of it is narcotics gang related. They argue over turf and get into violent disputes with each other, and that’s how people get hurt,” Chicago Police Supt. Garry McCarthy said at a press conference last month after a weekend of shootings claimed five lives and another 16 people were injured.

The numbers have become all too familiar in Chicago, as media organizations packaged homicide and shooting figures in customary roundup reports that followed weather and sports updates.

In June, as gun violence started to pile up, McCarthy announced the department would conduct a “gang audit” to help police better understand the problem’s scope. The work, a compilation of police stats, research and resident comments, was intended to provide the department with better information and a new laser-like focus.

The audit revealed what many have long suspected: The city has at least 59 gangs with 625 factions. But that got us thinking: Where, exactly, are these gangs operating out of?

WBEZ looked for online resources that can tell where particular gangs operate. The CPD’s online data portal, CLEARpath, presents all manner of data for the public and allows you to, for example, plot out where homicides occurred within a particular neighborhood. The tool doesn’t, however, lay out where the department suspects particular gangs operate, and no current website accomplished that either. The department only makes that information public through maps in a hardbound volume called The Gang Book, published by the Chicago Crime Commission. The most recent volume presents 2010 data, which was published in 2011.

WBEZ reproduced the flat maps depicted in the latest volume of The Gang Book and placed them in a more interactive format online. For the maps to be useful, we needed them to be searchable or at least browsable in a way that other maps informed by public data are. While fact-checking the boundaries we were drawing in a Google map, we asked the Chicago Police Department to supply gang territory data in commonly-used digital mapping formats (e.g., KML files use by Google maps). The department did not fulfill that request. Eventually (after we involved the Illinois Attorney General’s Office), the department provided flat, non-interactive maps that resembled those published in The Gang Book. The map you see below attempts to follow the contours laid out in those files.

A cursory look at the map reveals that gang territories appear to span all over the city’s South and West Sides, but also show up in pockets on the North Side. Also, according to the map, a territory can be as small as a city block, or as large as an entire police district or neighborhood.

CPD Chief of Organized Crime Nicholas Roti appeared on The Afternoon Shift to address several questions about the maps, their use and their limitations. On the question of why the department doesn’t dessiminate gang territory maps on its own website, he said such data is a double-edged sword. The department, he said, uses such information internally and, through the Commission’s gang book, shares it with suburban police departments.

But on the other hand, he said he’d be concerned if the maps are too easy to pass around. “We don’t want to either glorify a gang or maybe unintentionally cause a gang rift,” Chief Roti said. “You [a gang member] could look at a map and say, ‘They got way more territory than us.‘” 

Chief Roti also expressed concern about the possibility that such maps would stigmatize any particular Chicago neighborhood as being affiliated with gangs. “That not only goes into people buying homes,” he said. “That could go into businesses looking to start there.” 

Gang map with community areas

Gang map with schools
Source: City of Chicago’s data portal site was used for school locations. Some private and public schools have closed since the data was made available and may not be reflected on the map below.

Editor’s Note: Not all homicides in Chicago are gang-related, although police have said many of them are. The map below depicts all of the homicides year to date for 2012. Even with instances where police have identified homicides as “gang-related,” it would be harder to parse out which ones, especially for on-going investigations and cases.

Gang map with 2012 Homicides (Year to Date)
Homicide data provided courtesy of Tracy Swartz of the Chicago RedEye.