How Economic Development Is Changing the Geography of Urban Crime

Friday's tragic mass shooting at Sandy Hook Elementary is a harrowing reminder of the polar worlds of violent crime in this country. At the very same time that the murder rates in our cities are declining, mass killings, which tend to occur in the suburbs, are happening more often.

In an enlightening piece here on Cities on Monday, John Roman, an urban crime expert at the Urban Institute, took a detailed look at the declining homicide rates in America's largest 24 urban centers. After noting the caveats about lack of comparability of crime data between cities, he focused on data for "the one type of crime that is really hard to fake: homicide." Following a strategy originally introduced by The University of Chicago economist and Freakonomics co-author Steven Levitt, Roman arrayed these cities by the year their homicide rank peaked (about the early 1990s, when homicide rates peaked across the board in large cities), and compared this to their homicide rates in 2001 and 2010. In sync with previous research, he noted the overall decline in the homicide rate across all of these cities, and summarized Levitt's now-famous maxim: "the homicide decline was so consistent across cities that there was no need to think about local explanations."

But according to Roman, the nature of the change actually begs for a geographic explanation. On the one hand, a bunch of cities saw dramatic improvements in their homicide rates — New York, Washington, D.C., Los Angeles, Dallas, and Houston among them. On the other hand, there were cities that "are going in the wrong direction." While Las Vegas was the only city where the homicide rate actually increased, several cities moved up in the rankings — Columbus, Indianapolis, Milwaukee, Philadelphia, Baltimore, and Detroit.