Which States Have Reduced Their Prison Populations in the Past Decade?

By 2002, in the wake of a recession that caused major fiscal challenges in many states, there was an increasingly widespread recognition that the American imprisonment boom of the 1980s and 1990s was not economically sustainable.  Dozens of states adopted new sentencing and corrections policies that were intended to restrain further growth in imprisonment.  These reforms seem to have had some success, as imprisonment rates finally stabilized after so many years of explosive growth.  However, very little progress has been made toward bringing U.S. imprisonment rates back down to our historical norms.  The “if you build it, they will come” principle seems in evidence — after so much prison capacity was built in the boom years, we’ve found ways to keep using it even as crime rates have tumbled down.

A few states have had success, however, in downsizing their prison populations.  Here are the ten states whose prison populations dropped between December 2002 and December 2012:

New York             -19%
New Jersey           -17%
California             -16%
Connecticut          -15%
Michigan              -14%
Maryland              -9%
South Carolina     -5%
Wisconsin             -5%
Rhode Island        -2%
Hawaii                  -1%

Even the largest decreases on the list are rather small compared with the size of the pre-2002 increases.  Nonetheless, some might wonder whether reduced imprisonment has resulted in more crime.  With that concern in mind, I gathered data on violent crime in the five states that experienced double-digit drops in imprisonment.  

More specifically, I compared violent crimes in the 2000-2002 time period with violent crimes in 2010-2012.  As you can see, instead of becoming more dangerous, all five states saw reductions in violence:

New York             -22%
New Jersey           -18%
California             -24%
Connecticut          -10%
Michigan              -17%

The scale of the crime reduction in each state is remarkably close to the scale of the imprisonment reduction.  This is an interesting finding, which suggests that a major driver of imprisonment reduction has simply been a diminishing number of serious offenders available to put behind bars.

Does this mean that sentencing and corrections policies have played no role?  Not necessarily.  Even in the face of declining violent crime, criminal-justice systems are able to keep prison beds filled, for instance, through stepped-up drug enforcement or more aggressive supervision and revocation of probationers and parolees.  States that have realized imprisonment reductions commensurate with their crime reductions may, to some extent, be able to credit policies that have held the “if you build it, they will come” pressures in check.

California, in particular, seemed unable to translate reduced crime rates into reduced imprisonment until forced to do so by a court order.  Then, in the first year after the state adopted its Public Safety Realignment Act, the prison population finally dropped by an extraordinary 25%.  The effect on public safety?  In the short run, violent crime ticked up by a modest 4%, which is within the typical range of year-to-year variations. Determining whether and to what extent the PSRA has durable public-safety costs is an important project that will surely keep researchers occupied for many years.