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While states and the federal government have modestly reduced their prison populations in recent years, incarceration trends continue to vary significantly across jurisdictions. Overall, the number of people held in state and federal prisons has declined by 4.9% since reaching its peak in 2009. Sixteen states have achieved double-digit rates of decline and the federal system has downsized at almost twice the national rate. But while 38 states have reduced their prison populations, in most states this change has been relatively modest. In addition, 12 states have continued to expand their prison populations even though most have shared in the nationwide crime drop.

Six states have reduced their prison populations by over 20% since reaching their peak levels:

  • New Jersey (35% decline since 1999)
  • New York (29% decline since 1999)
  • Alaska (27% decline since 2006)
  • California (26% decline since 2006, though partly offset by increasing jail use)
  • Vermont (25% decline since 2009)
  • Connecticut (22% decline since 2007)

Southern states including Mississippi, South Carolina, and Louisiana, which have exceptionally high rates of incarceration, have also begun to significantly downsize their prison populations. These reductions have come about through a mix of changes in policy and practice designed to reduce admissions to prison and lengths of stay. Moreover, the states with the most substantial prison population reductions have often outpaced the nationwide crime drop.

The pace of decarceration has been very modest in most states, especially given that nationwide violent and property crime rates have fallen by half since 1991. Despite often sharing in these crime trends, 15 states had less than a 5% prison population decline since their peak year. Moreover, 12 states have continued to expand their prison populations, with four producing double-digit increases since 2010: North Dakota, Wyoming, Oklahoma, and Minnesota.

Just as mass incarceration has developed primarily as a result of changes in policy, not crime rates, so too have declines reflected changes in both policy and practice. These have included such measures as drug sentencing reforms, reduced admissions to prison for technical parole violations, and diversion options for persons convicted of lower-level property and drug crimes.

Change in state and federal prison populations
Jurisdiction Peak Year to 2015 Peak Year
New Jersey -34.9% 1999
New York -29.2% 1999
Alaska -27.4% 2006
California -25.7% 2006
Vermont -25.2% 2009
Connecticut -22.1% 2007
Michigan -17.4% 2006
Maine -16.2% 2007
Mississippi -16.0% 2008
Hawaii -14.8% 2005
Rhode Island -14.5% 2008
Colorado -13.9% 2008
Massachusetts -13.2% 2011
South Carolina -13.2% 2009
Idaho -12.0% 2012
Maryland -10.4% 2007
Louisiana -9.5% 2012
Federal -9.3% 2011
Indiana -8.6% 2013
Utah -8.3% 2013
Georgia -6.9% 2009
Illinois -6.3% 2012
Iowa -6.1% 2010
Alabama -5.3% 2012
US total -4.9% 2009
Texas -4.5% 2010
Wisconsin -3.8% 2006
Pennsylvania -3.5% 2011
South Dakota -3.1% 2013
Florida -2.8% 2010
Nevada -2.3% 2007
Tennessee -2.1% 2014
New Hampshire -1.1% 2007
Arkansas -0.9% 2014
Montana -0.8% 2010
North Carolina -0.7% 2014
Nebraska -0.7% 2014
Kentucky -0.6% 2007
Delaware -0.3% 2007
Washington 0.0% 2010
Change in state and federal prison populations
Jurisdiction 2010 to 2015 Peak Year
Ohio 1.0% 2015
Virginia 2.7% 2015
Oregon 2.7% 2015
Missouri 5.6% 2015
New Mexico 5.7% 2015
Kansas 5.8% 2015
Arizona 6.6% 2015
West Virginia 7.2% 2015
Minnesota 10.2% 2015
Oklahoma 14.7% 2015
Wyoming 14.8% 2015
North Dakota 19.9% 2015
Source: Prisoners Series (1999-2015), Bureau of Justice Statistics.
Note: Idaho and Illinois data may not be fully comparable across years.
U.S. prison population trends through 2015: decreases from peak year, increases from 2010
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Source: Prisoners Series (1999-2015), Bureau of Justice Statistics.
Note: Idaho and Illinois data may not be fully comparable across years.