2.23 arrests per night. In just 200 days, the four officers had done more “policing” than most officers of that era did in their entire careers: 1,090 traffic citations, 948 vehicle stops, 616 arrests, 532 pedestrian checks, and 29 guns seized. That’s one police intervention every forty minutes. On a given night in the tiny 0.64 square miles of 144, each squad car drove about twenty-seven miles. The officers weren’t parked on a street corner, eating doughnuts. They were in constant motion.
Police officers are no different from the rest of us. They want to feel that their efforts are important, that what they do matters, that their hard work will be rewarded. What happened in District 144 provided exactly what the profession of law enforcement had been searching for: validation.
“Officers who recovered a firearm received favorable notoriety from their peers, almost to the point that recovery of a firearm came to be a measure of success,” Shaw wrote in his account of the program. “Officers could frequently be heard making statements such as ‘I’ve just got to get a gun tonight,’ or ‘I haven’t gotten a gun yet; tonight will be the night!’”
In 1991 the New York Times ran a front-page story on the miracle in Kansas City. Larry Sherman says that over the next few days his phone rang off the hook: 300 police departments around the country bombarded him with requests for information on how he had done it. One by one, police departments around the country followed suit. To give one example, the North Carolina State Highway Patrol went from 400,000 to 800,000 traffic stops a year in the space of seven years.
The Drug Enforcement Agency used “Operation Pipeline” to teach tens of thousands of local police officers across the United States how to use Kansas City–style traffic stops to catch drug couriers. Immigration officials started using police stops to catch undocumented immigrants. Today, police officers in the United States make something like twenty million traffic stops a year. That’s 55,000 a day. All over the United States, law enforcement has tried to replicate the miracle in District 144. The key word in that sentence is tried. Because in the transition from Kansas City to the rest of the country, something crucial in Lawrence Sherman’s experiment was lost.
4.
The Lawrence Sherman who went to Kansas City is the same Larry Sherman who had worked with David Weisburd in Minneapolis a few years earlier, establishing the Law of Crime Concentration. They were friends. They taught together for a time at Rutgers, where their department chairman was none other than Ronald Clarke, who had done the pioneering work on suicide. Clarke, Weisburd, and Sherman—with their separate interests in English town gas, the crime map of Minneapolis, and guns in Kansas City—were all pursuing the same revolutionary idea of coupling.
And what was the principal implication of coupling? That law enforcement didn’t need to be bigger; it needed to be more focused. If criminals operated overwhelmingly in a few concentrated hot spots, those crucial parts of the city should be more heavily policed than anywhere else, and the kinds of crime-fighting strategies used by police in those areas ought to be very different from those used in the vast stretches of the city with virtually no crime at all.
“If crime is concentrated on a few percent of the city streets,” Weisburd asked, “why the hell are you wasting resources everywhere? If it’s coupled to those places and doesn’t move easily, even more so.” The coupling theorists believed they had solved the problem that had so confounded the earlier days of preventive patrol. How do you effectively patrol a vast urban area with a few hundred police officers? Not by hiring more police officers, or by turning the entire city into a surveillance state. You do it by zeroing in on those few specific places where all the crime is.
But think back to those statistics from North Carolina. If you go from 400,000 traffic stops in one year to 800,000 seven years later, does that sound like focused and concentrated policing? Or does that sound like the North Carolina State Highway Patrol hired a lot more police officers and told everyone, everywhere, to pull over a lot more motorists? The lesson the law-enforcement community took from Kansas City was that preventive patrol worked if it was more aggressive. But the part they missed was that aggressive patrol was supposed to be confined to places where crime was concentrated. Kansas City had been a