In early June, The Economist published an article showing declining U.S. crime rates. The magazine posed an interesting question:
Why does crime continue to decline in the United States, even when unemployment is high?
According to The Economist, violent crime fell by 5.3% between 2008 and 2009, and by another 5.5% from 2009 to 2010. According to my own calculations, the national crime rate fell by nearly 61% from 1990 to 2008.
This result seems counterintuitive, because one would think that criminals would be more motivated to commit crimes during an economic downturn.
However, the data suggests a weak positive correlation between the unemployment rate and the national crime rate.
Source: U.S. Census Bureau, U.S. Bureau of Labor Statistics
So what is driving the crime rate down?
There are several explanations.
Some have argued that the increased availability of legal abortions since the 1970s have resulted in “fewer children born to teenagem, unwed and poor mothers.” Since these children would be more likely to grow up and commit crimes, aborting them would result in a lower crime rate 20 years later according to this theory.
Another explanation for the decline in crime is an increased incarceration rate. In fact, from 1990 to 2008, the crime rate had a -98.5% correlation with the incarceration rate. The more people the country incarcerated, the more the crime rate declined.
Source: U.S. Census Bureau
Another interesting theory is that the decline in American children’s exposure to lead as a result of lead’s phase out from gasoline and paint in the 1970s, is linked to lower aggression in adults. In fact, I looked at the correlation between lead concentration in the air and the crime rate. It turns out that the two are 72.1% correlated.
Source: U.S. Census Bureau, EPA
Al Blumstein has proposed what I consider to be the most absurd explanation, the so-called “Obama effect.” According to this theory, the election of the United States’ first African-American president inspired a “significant number of young black men away from violence.”
Ridiculous.
Reflections of a Rational Republican 
The culture of black youth has changed. Fewer drug addicts, teenage mothers, church attendance, less materialistic and simply less confrontational.
Shon,
Perhaps.
However, I think it is something larger as crime rates are down across the board for all races.
One possibility — also an anomaly — is the decline in illegal drug use, which the NIH has reported over the past 6 years.
I did not know that drug use was down. I wonder what is driving it.
A friend of mine, who is an expert in this field, has suggested that most crimes are due to one of two factors — the criminal is either a drug user or a sex criminal. He noted that recitivism rates are predictable for ex-cons who kick their drug habits. For sex criminals, not so much.
The bottom line is that I suspect your thesis is probably a big driver as well, if not one of the top three.