Giuliani won the election and selected Boston police chief Bill Bratton as the NYPD’s new commissioner. Bratton aggressively cracked down on small crimes, believing bigger crimes would drop as well. And they did.
But in fact, violent crime had actually peaked in New York City in 1990, four years before the Giuliani-Bratton era. By the time they took office, it had already dropped 12 percent. And it continued to drop. And drop. And drop. By 2010, violent crime rates in New York City had plunged 75 percent from their peak in the early ’90s.
It’s not just New York that saw a big drop in crime. In city after city, violent crime peaked in the early ’90s and then began a steady and spectacular decline. Washington, DC, didn’t have either Giuliani or Bratton, but its violent crime rate dropped 58 percent since its peak. Dallas’ fell 70 percent. Newark: 74 percent. Los Angeles: 78 percent.
The disappearance of lead from gas and paint is one of the most compelling hypotheses to explain the decline of violent crime in America, especially in cities — big cities, with their density and traffic, were particularly vulnerable to airborne lead.
It’s the only hypothesis that persuasively explains both the rise of crime in the ’60s and ’70s and its fall beginning in the ’90s. Two other hypotheses — the baby boom demographic bulge and the drug explosion of the ’60s — at least have the potential to explain both, but neither one fully fits the known data. Only gasoline lead, with its dramatic rise and fall following World War II, can explain the equally dramatic rise and fall in violent crime. In fact, gasoline lead may explain as much as 90 percent of the rise and fall of violent crime over the past half century.
Having said that, it’s important to note that the evidence so far is not conclusive in favor of any of the hypotheses.
- Howard W. Mielke, Sammy Zahran. The urban rise and fall of air lead (Pb) and the latent surge and retreat of societal violence. Environment International, 2012; 43: 48 DOI: 10.1016/j.envint.2012.03.005
- Rick Nevin. How Lead Exposure Relates to Temporal Changes in IQ, Violent Crime, and Unwed Pregnancy. Environmental Research, May 2000; 83 (1): 1-22