By the early 1990s, New York City had experienced more than two decades of rising crime. New York City’s 1975 fiscal crisis—the city nearly went bankrupt—prompted a brutal series of budget cuts, including 5,000 layoffs in the NYPD. ^[4] By 1980, the department had lost another nearly 8,000 officers to attrition; taken together, the department had shrunk by about 34 percent, even while the rate of serious crime rose 40 percent. ^[5] Smaller offenses like vandalism and vagrancy proliferated largely unchecked, contributing to an overall sense of disorder and chaos.

“There was this sense that New York was declining, and that crime was a critical part of that,” says Professor Dennis Smith , an expert on public policy and performance management. ^[6] Rudolph Giuliani won New York’s November 1993 mayoral election with promises to crack down on crime. ^[7] On January 10, 1994, Mayor Giuliani installed William J. Bratton as commissioner of the NYPD.

Bratton had overseen a reduction in subway crime as chief of the New York City Transit Police from 1990-92. Embracing the novel “broken windows” theory of policing, which posited a link between general disorder and serious crime, the transit police under Bratton aggressively enforced lower-level infractions such as farebeating. The logic was that by cracking down on minor infractions, NYPD could prevent more serious crimes. In his first six months with the Transit Police, Bratton oversaw a spike in summonses, ejections, and arrests in the subway, and subway crime fell. ^[8]

New job . In 1994, Bratton took the helm of a much larger and more complex organization than his previous assignment at the Transit Police: some 50,000 police officers responsible for the public safety of 7 million New Yorkers spread throughout 76 precincts. Yet he and his team had some advantages. Former Mayor David Dinkins had expanded NYPD resources with an initiative called Safe Streets, Safe Cities, which authorized the NYPD to hire some 6,000 officers. “Crime had already started going down a little bit” at the end of the Dinkins administration, says Smith. “[The NYPD] already had this pipeline of more officers coming in… And it gave Commissioner Bratton the opportunity to innovate.” Police departments across the country had to devote significant resources to meeting standards such as average response time to 911 emergency calls, says Smith, but with money and officers flowing into the department, Bratton had space both to maintain traditional standards and experiment with other policing strategies.

Professor Dennis Smith: video.

Real-time statistics. Bratton believed that the Police Department was capable not just of responding to crime, but of proactively preventing it. To do so, however, would require detailed knowledge of where crimes were most likely to occur, and a strategic and timely deployment of resources. The NYPD already knew a lot about crime. The department had been an epicenter of what later came to be known as “big data” since at least the 1970s, when it became one of the first US cities to institute a 911 emergency call system. “Almost immediately, there were [millions of] calls a year to the police department,” says Smith. ^[9] The department had long used data from these calls and other sources to create precinct-specific pictures of crime patterns.

But the reports were compiled quarterly, so data was already four months old by the time it reached police commanders. Though detailed, the reports provided “management information history” rather than a basis for decisions, says Smith. With crime patterns that shifted on a weekly or even daily basis, Bratton felt police resources should move correspondingly. Says Smith:

When you decide you’re going to actually try to get on top of crime, you’re going to fight crime, you’re going to fight it block by block, you need to have information that is more timely, more disaggregated, and given attention of a different kind than it had [been] in the past.

But implementing a new decision system was not going to be easy. For example, when the new deputy commissioner for crime control strategies, Jack Maple, wanted the previous day’s crime figures, he was told it would take six months to get. Bratton recalls his dismay: “The largest police department in America was going to take six months to tell us what happened yesterday in New York City.” ^[10]