This is my block, no, it's not. i'm going show you whose block it is. >> evanston's not the only community battling an influx of gang activity from the city. it's a wide spread phenomenon fuelled in part by the closing of chicago's public housing projects. now, gangs are sprawling into 88% of the suburbs throughout cook county. >> chief of police asked me, how do you know you have a gang problem? i tell him, chief, i have this. i understand what this stuff means. i can't be a gang expert if i don't know what this means. >> one of the best places to track the chicago area's 70 plus gangs, estim...