This is a longer, more detailed, and more statistics-laden version of an op ed piece that ran in the Financial Times on Friday. As mysterious as the downward trend in crime may be (and as vexing a challenge as itâ€™s posed to professional explainers), itâ€™s obviously a welcome developmentâ€”and is very possibly a bellwether of even more positive changes in our society.
Almost three years into the worst economic downturn since the Great Depression, with massive unemployment and pessimism rife, Americaâ€™s crime rates are falling and no oneâ€”not our pundits, policemen, or politicians, our professors or city plannersâ€”can tell us why. As I wrote about here, there were 5.5 percent fewer murders, forcible rapes, robberies and aggravated assaults reported in 2010 than in 2009, according to the most recent edition of the FBI’s Uniform Crime Report; property crimes fell by 2.8 percent over the same period and reported arsons dropped by 8.3 percent. And the drop was steepest in Americaâ€™s biggest citiesâ€”which are still popularly believed to be cauldrons of criminality. â€śWhile cities and suburbs alike are much safer today than in 1990,â€ť notes a recent report by the Brookings Institution, â€ścentral citiesâ€”the big cities that make up the hubs of the 100 largest metro areasâ€”benefitted the most from declining crime rates. Among suburban communities, older higher-density suburbs saw crime drop at a faster pace than newer, lower-density emerging and exurban communities on the metropolitan fringe.â€ť
An essay in The Economist featured a graphic which charts the arc of American crime rates since the 1960s. Its caption poses the question that is on everyoneâ€™s lips:
Some explanations evoke Sherlock Holmesâ€™ â€śdog that didnâ€™t bark.â€ť When crime rates first began to fall in the 1990s, Steven Levitt and John Donohue III argued that legalized abortion was responsible, since unwanted children would have been more likely to grow up to be criminals â€“ a finding that was not only wildly controversial but has been met with substantial challenge. Research by economist Jessica Wolpaw Reyes find attributes a significant proportion of the decline in violent crime to childrenâ€™s reduced exposure to lead.
Others suggest that Americaâ€™s astronomical incarceration rateâ€”the highest in the worldâ€”is responsible, though that begs the question why countries that donâ€™t incarcerate their citizens at anything like the same rate suffer from less crime than the US does. Itâ€™s disquieting to think that what would seem to be an unalloyed social goodâ€”less crimeâ€”might have been brought about in part by what many believe to be a social disaster: Americaâ€™s draconian, unequally enforced drug laws. Still, law enforcement must be given its due; many big city police departments have developed statistically-driven methodologies for targeting crime hot-spots, with conspicuously successful results. And we as individuals have changed our behavior as wellâ€”from taking elementary precautions like locking our doors, to investing in crime-stopping technology like burglar alarms for our homes and LoJack for our cars.
Still, it is confounding that crime would decline as economic conditions worsen. My own analysis, conducted with my Martin Prosperity Institute colleague Charlotta Mellander, turns up no statistical associations between crime and either the level or the change in the level of unemployment across metros, or between crime and the level of income inequality. There does seem to be a modest relationship between the absolute poverty rate and crime. Our analysis turned up an association of .19 between crime and the percent of population below the poverty line. But it has weakened substantially over the past two or three decades, according to the Brookings study.
So too has the relationship between crime and race. From evening news headlines to crime shows on TV, popular culture underlines the propinquity between crime and race Our analysis turned up modest correlation (.37) between crime and the share of population that is black. But again, Brookings Institute report assembles powerful evidence to show that the relationship has been weakening. â€śThe association between crime and community characteristicsâ€”like the proportion of the population that is black, Hispanic, poor, or foreign-bornâ€”diminished considerably over time,â€ť notes the study. â€śThe strength of the relationship between the share of black residents and property crime decreased by half between 1990 and 2008, while the association between the share of Hispanic residents and violent crime all but disappeared.â€ť
In the popular imagination, crime is frequently associated with big, densely populated cities. Here again, we can separate fact from myth.Â Primary cities and older high-density suburbs exhibited the largest decreases in crime between 1990 and 2008, according to the Brookings study. And the gap between city and suburban violent crime narrowed in two-thirds of the nationâ€™s 100 largest metro areas. Our own analysis turns up no association whatsoever between metro size or metro density and the overall level of crime, though we do find a modest correlation (.25) between density and violent crime.
In a thoughtful essay in the Wall Street Journal, the distinguished political scientist and urban crime expert James Q. Wilson hit hard at strictly economistic explanations, suggesting that deeper changes in American culture can better account for the mystery. â€śThe cultural argumentâ€ť he writes, can help explain not only the current drop in crime, but also â€śthe Great Depression’s fall in crime and the explosion of crime during the sixties. In the first period, on this view, people took self-control seriously; in the second, self-expressionâ€”at society’s costâ€”became more prevalent.â€ť My former Carnegie Mellon University colleague, the distinguished criminologist Alfred Blumstein, proposes an â€śObama effect,â€ť in which young black malesâ€™ increased optimism about their futures makes them more likely to refrain from violence.
But the key factor, as it turns out, lies in the growing racial, ethnic, and demographic diversity of our cities and metro areas. Our analysis found that the Hispanic share of the population is negatively associated with urban crime. Crime also fell as the percentage of the population that is non-white and the percentage that is gay increased. And of all the variables in our analysis, the one that is most consistently negatively associated with crime is a placeâ€™s percentage of foreign-born residents. . Not only did we find a negative correlation (-.36) between foreign-born share and crime in general, the pattern held across all of the many, various types of crime â€“ from murder and arson to burglary and car theft. The Brookings study also finds evidence of a substantial shift in the connection between foreign-born residents and crime. While foreign-born share was positively associated with crime in 1990 and 2000, that relationship had disappeared by 2008. The foreign-born share of population now shows no relationship to property crime, and a negative relationship to violent crime. The pattern is most pronounced for primary cities and inner-ring suburbs, the Brookings study found, but not for lower-density suburbs and ex-urbs.
It might be hard to wrap your mind around thisâ€”especially with all the demagoguery about immigration. But the numbers tell a different story than our alarmist pundits and politicians do. â€śSince 1990, all types of communities within the countryâ€™s largest metro areas have become more diverse,â€ť Elizabeth Kneebone, one of the authors of the Brookings report, wrote in The New Republic. â€śCrime fell fastest in big cities and high-density suburbs that were poorer, more minority, and had higher crime rates to begin with. At the same time, all kinds of suburbs saw their share of poor, minority, and foreign-born residents increase. As suburbia diversified, crime rates fell.â€ť Along with their entrepreneurial energy and their zeal to succeed, immigrants are good neighborsâ€”cultural and economic factors that militate against criminal behavior, and not just in their own enclaves but in surrounding communities as well.
One additional factor bears on this. Our analysis also turns up a consistent negative correlation between crime and the overall level of city happiness. It makes intuitive sense that a low-crime city would be a happy city; still, itâ€™s worth pointing out that the happiness measure (which comes from Gallup surveys) is associated not just with overall crime but with almost every type of crime across the board. This is somewhat striking in an analysis where associations between crime and key social and economic variables are hard to find. More to the point, the Gallup research identifies openness to diversity as being one of the two most important factors that shape city happiness and community satisfaction across the board.
Americaâ€™s declining crime rates are cause for celebration, even if we canâ€™t completely explain the phenomenon. The fact that diversity appears to play such a signal role in the trendâ€”something that most Americans regard as a moral and economic good in its own rightâ€” makes it all-the-more satisfying.