zlacker

Your hypothesis isn't the only plausible one. Have you considered that more crime = more inmates, sentences aside?

First: since you go to prison after the crime, the inmate population size should be a trailing indicator of the crime rate. More serious crimes affect the prison population for a long period, since their sentences are longer.

Second: take a look at these graphs, and how dramatically they shoot up around 1965:

http://www.wolframalpha.com/input/?i=murder+USA

http://www.wolframalpha.com/input/?i=rape+USA

http://www.wolframalpha.com/input/?i=crime+USA

>>notadd+(OP)
Why does the data collection only start in 1960? The fact that the rates shoot up five years after they start collecting data might just mean that for the first five years, the data collection system was just getting ramped up.

>>notadd+(OP)
All of those graphs show peaks in the early 1990s and a decline after then. That's long enough that if the number of crimes was the main causal factor, prison numbers would be going down by now.

>>notadd+(OP)
Demographics are a major factor in the increase you cite. A disproportionate amount of crime is caused by men in their late teens and early twenties. The Baby Boom caused a rapid increase in that, with predictable results.

Another factor is greatly improved reporting. Rape in particular used to be very poorly reported, and this has improved a lot as the social stigma against reporting it lessened. The shape long rise from the 60s to 1990 was certainly strongly affected by that.

A number of reasons exist for the recent drop in very violent crime that the murder graph shows. Demographics are surprisingly only a small part of it. Most of it was the result of public health efforts that reduced the incidence of lead poisoning. See http://www.washingtonpost.com/wp-dyn/content/article/2007/07... for more. A much smaller factor which many have heard of was the legalization of abortion. While this has an effect, and was popularized in Freakonomics, the effect was much less than the benefit of reduced lead poisoning.

>>notadd+(OP)
The Freakonomics guys correlated the drop in crime in the 90's to the legalization of abortion in the 70's, and others think that the drop in crime is a byproduct of the tougher three strikes rules states have adopted. I'm just speculating, of course, but I wonder whether the internet has been a factor in the drop off. Less boredom = less crime?

>>cabala+91
The issues are basically correct on both sides, however there exists the problem fact that while prison populations are - and have been on the increase - actual crime rates have been declining over the past decade plus. This is indicative that while crime has been diminishing, arrests and convictions for existing laws have been increasing disproportionately. The reason for the "peak" in the stats in the 90's is partially due to the discovery by private prison investors and private sector corporations of the federal PIECP program. This program allows partnerships between private sector companies and prison industries to use prison labor to manufacture their products or provide their services, which allows lower overhead and increased profits. In the mid 90's corporate America discovered the program and began to manipulate it. At the same time, prison numbers began to increase while the crime rate declined. This was a direct result of the realization of the amount of labor needed to fully exploit the program.To use the program to the maximum benefit, there had to be a continuous supply of manpower - whether the crime rate was holding steady or in decline.

>>nhebb+m7
I wouldn't put much weight on that study.

http://en.wikipedia.org/wiki/The_Impact_of_Legalized_Abortio... http://www.isteve.com/abortion.htm http://www.slate.com/id/33569