While it is unclear how to prevent mass shootings—short of the unlikely event of removing all guns from the public—we know how to reduce urban violence: data-driven, proactive policing. The New York Police Department has brought crime and homicide down an unmatched 80 percent since the early 1990s by deploying officers to locations where crime patterns are emerging, encouraging them to use their lawful discretion to question people about suspicious behavior, enforcing quality-of-life laws, and holding police commanders accountable for crime on their watch.

Gun control has had only a limited effect on inner-city violence, as the case of Chicago demonstrates. Despite the Windy City’s strict firearms bans, juveniles under the age of 17 are killed there four times as often as youth in New York. In 2012, Chicago logged 506 homicides; New York, with three times the population, tallied 418. The difference lies largely in policing. Chicago has historically eschewed proactive policing, and is for that reason still embraced by the left—however incredibly—as a model for law enforcement. Some South Side community leaders, however, know better and are calling for the reconstitution of antigang units just so their officers can stop and question more suspects on the streets.

Whereas Chicago’s minority neighborhoods are awash in illegal guns, criminals in New York report leaving their guns at home or stashing them in communal locations to avoid being stopped with a gun on their person. As a result, 10,000 homicides of minority victims have been averted since the early 1990s. And by lowering violence and fear, proactive policing has done more to revitalize poor neighborhoods than billions of dollars of government-funded social programs have ever accomplished.