I only really started thinking about community policing strategies after I started watching the HBO program The Wire. That show attempted to show the difficulty of policing a large urban area with lots of gang and drug activity. At one point, a police captain essentially legalized drugs in one area of the city. He said, if you sell or buy drugs here, I won’t bother you. But if you sell or buy them anywhere else, I will crack down hard on you. It seemed to actually work for a while. His precincts showed a significant reduction in violent crime. The problem was that he wasn’t authorized to legalize drugs anywhere in the city and he had to attempt to keep his plan secret. There was no way that could last, and the whole thing fell apart.

If you look at patterns of violence in our cities, you’ll recognize that there are good (safe) neighborhoods and bad (dangerous) neighborhoods, and that these neighborhoods tend to stay the same or evolve very slowly. I haven’t lived in Philadelphia for seven years, but I probably still have an accurate mental map of where I can safely go and where I should avoid.

Because of this, the police can identify bad neighborhoods or “problem corners” and they can focus their attention there. It may seem like this would be totally ineffective because it’s like squeezing a balloon. The violence doesn’t go away, it just moves to an adjacent neighborhood. But this isn’t always the case. Sometimes, the violence just stops. An article in Wired might help to explain why. If you think of violence as a disease like cholera, you can see how it can spread through exposure and it can be stamped out by targeted efforts. Basically, start with the assumption that the number one cause of violence is exposure to violence. It’s not the only cause, but it is very important because of its self-perpetuating nature.

This is why one neighborhood may maintain a violent character over a sustained period of time without spreading to nearby neighborhoods. It’s also why clamping down on violence in a bad neighborhood will not necessarily cause that violence to move elsewhere. It doesn’t have to be a never-ending game of whack-a-mole.

One of the interesting things in the article is the revelation that maps of violent crimes in our cities look just like maps of cholera outbreak in Bangladesh. This suggests that it may be possible to limit violent crime by tracking and mapping its occurrence very closely and treating it like we treat an outbreak of disease. Stop the uptick in violence early and you can contain it enough that it will burn itself out.

It also suggests that you can do your own part to reduce violence by not being violent yourself. Don’t spread the virus.