Over the past 30 years, the United States has experienced an unprecedented rise in the use of incarceration, with the number of people in prisons and jails increasing from 330,000 in 1972 to more than 2.3 million today. While the United States represents about 5 percent of the world’s population, it houses around 25 percent of the world’s prisoners. The crime rate over the last decade plunged to levels not seen in generations. Why? And why hasn’t there been a concomitant drop in the incarceration rate?

No Connection Between Incarceration and Crime

Some experts have postulated that crime has fallen because all the criminals have been locked up. But the data doesn’t support this theory. A number of states with large increases in incarceration over the last 30 years experienced smaller drops in crime than did states that increased their use of imprisonment at a lower rate. For example, Texas, with a 144 percent increase in incarceration, and California, with a 52 percent increase, experienced considerable declines in crime (35 percent and 36 percent respectively), but New York experienced a 43 percent decline in crime despite an increase in incarceration of only 24 percent. An overview of changes in incarceration and crime in all 50 states reveals no consistent relationship between the rate at which incarceration increased and the rate at which crime decreased.

In Fact, Some Studies Say More Incarceration, More Crime

A recent study that analyzed state prison and crime data revealed that there was no discernible pattern of states with higher rates of increase in incarceration experiencing more significant declines in crime. Between 1991 and 1998, those states that increased incarceration at rates that were less than the national average experienced a larger decline in crime rates than those states that increased incarceration at rates higher than the national average. Since 1998, 12 states experienced stable or declining incarceration rates, yet the 12 percent average decrease in crime rates in these states was the same as in the 38 states in which rates of imprisonment increased. If incarceration was having the impact on crime that proponents suggest, then those states with higher increases in incarceration rates should have experienced more substantial declines in crime rates.