A BBC report (thanks Magic) tries to surmise why violent crime rates in the United States have dropped dramatically in the last twenty years. The report offers ten possible reasons for this including The Obama presidency, good police work, the fall in demand for crack cocaine, police department number crunching, aging baby boomers, a decline in children's exposure to lead in petrol, more criminals behind bars, and a controversial theory that the increased availability of legal abortion has had an impact on population in poorer neighborhoods.
But the most interesting reason comes in at number nine. That entry cites a recent study conducted by researchers in Texas working with the Centre for European Economic Research. From the article: