Plagued by all manner of urban ills, post-War American cities were not the cause celebre they are today. While the suburban ideal pulled people out of the city, they were also pushed out by popular perceptions of crime, drugs and moral depravity. Of these, the perception of crime was perhaps the most profoundly resonant issue as young families fled cities seeking safe places to raise families. In the process, the city itself was demonized: a uncivilized place, fit only for uncivilized people.
But what if it wasn't the city that was increasing crime, but rather an unintended consequence of suburbanization? That's the compelling hypothesis advanced by Kevin Drum, writing in Mother Jones, who summarizes wide-ranging research correlating the rise in violent crime not to drug use, racial tensions or class warfare, but rather to a GM-created compound found in gasoline: tetraethyl lead. He writes:
We now have studies at the international level, the national level, the state level, the city level, and even the individual level. Groups of children have been followed from the womb to adulthood, and higher childhood blood lead levels are consistently associated with higher adult arrest rates for violent crimes. All of these studies tell the same story: Gasoline lead is responsible for a good share of the rise and fall of violent crime over the past half century.
Covering the story for Planetizen, Josh Stephens (who came up with the slogan on the doctored Daily News image above), makes the connection to these findings and contemporary urban planning. He praises Drum's research because urbanists can now articulate a root cause to the epidemic of crime, empowering them to demystify it. Stephens writes:
The Lead Age, such as it was, created a vicious cycle: violence begat violence, fear begat flight, flight begat abandoned cities, and abandoned cities created a rational motivation for crime where once only chemical imbalance had ruled the day. A virtuous cycle can replace the vicious one. The collective bloodstream is being diluted of its poison. We can roar back to the cities—as younger Americans have already been doing—and with that we can seek new means of prospering. We can start by spending losing less money to crime and less emotional energy to fear.
Stephens' idealism is being borne out by new data. Given the precipitous decline in leaded gasoline use we would expect that urban areas today are safer than they were in the 60s and 70s. And they are, as the graph above shows. But even more remarkable is the fact that cities (or more accurately "mixed use zones" like those found in Jane Jacobs' Greenwich Village or Jerry Seinfeld's Upper West Side) are, in fact, demonstrably safer than the isolated land use islands filled with commercial uses.
Though the linked study does not hazard a guess for this relationship, we might speculate that the land use diversity helps to create a kind of resilient public safety that protects an areas' residents and businesses. Due to the presence of people who live there, there is a constantly evolving, but utterly necessary negotiation of norms between dissimilar groups that breeds a respectful recognition that the best way to stay safe is to stay within the unspoken limits of your neighbors' understanding of appropriate behaviors.