After nearly four decades of explosive growth, the U.S. prison population declined for two years in a row, according to the Justice Department. Inmate counts fell in about half the states in each year from 2009-10 and 2010-11. 
Over the past five years, the imprisonment rate fell in 29 states. California, which was ordered by the U.S. Supreme Court to reduce its prison population, led the way with a 17 percent drop. Nine other states reduced their imprisonment rates between 2006 and 2011 by double digits: Hawaii (16 percent), Massachusetts (15 percent), Michigan (15 percent), New Jersey (14 percent), Alaska (13 percent), New York (13 percent), Connecticut (11 percent), Delaware (10 percent), and South Carolina (10 percent).
At the other end of the spectrum, West Virginia had the highest level of growth among 20 states that increased in their imprisonment rates, rising by 17 percent. Other growth leaders include Arizona (16 percent), Pennsylvania (14 percent), Arkansas (12 percent), Alabama (9 percent), Indiana (8 percent), Illinois (7 percent), Florida (6 percent), and Mississippi and Tennessee (5 percent each).
Many of the states showing recent drops have taken substantial steps to rein in the size and cost of their corrections systems. Often with overwhelming bipartisan votes, leaders in these states have shortened terms behind bars for lower-level offenders or diverted them from prison altogether. Several states, including Georgia and Pennsylvania during their 2012 legislative sessions, reinvested large sums of the resulting savings into probation and parole in an effort to break the cycle of recidivism and improve public safety.
Conventional wisdom holds that the movement to contain prison growth is about saving money. Tight budgets surely invited scrutiny of the $50 billion that states together spend on corrections, but there are three more important drivers of change:
Crime is down both in states that continued with (and paid for) rapid prison growth and those that did not. Researchers agree the national incarceration rate—nearly 1 in 100 adults is behind bars—is yielding diminishing public safety returns. Nationally, 29 states reduced their imprisonment rates over the past five years, and the crime rate went down in all but three of them.
Californians sent a strong version of this message on Election Day, with 69 percent of voters approving a ballot measure scaling back the state’s once-popular three-strikes law. Key stakeholder groups in many states also support reforms, including business and faith leaders, police chiefs, and victims’ advocates. Some of the strongest calls for change come from the Right on Crime initiative, which boasts high-profile conservative members such as Jeb Bush, Newt Gingrich, William Bennett, Ed Meese, and Grover Norquist.
When lower-risk and lower-level offenders are diverted from prison to community programs, new supervision technologies provide confidence that these offenders still can be held accountable for their behavior. Research also has recognized new strategies that effectively change offender behavior, including mandating cognitive-behavioral therapies that improve impulse control, imposing swift and certain sanctions for rule violations, and offering rewards for staying crime- and drug-free.
This powerful alignment of research, public opinion, and state successes suggests that the recent downturn in the prison population and shift to proven alternatives is not merely a function of tight fiscal times, but rather an evidence-based policy change that is likely to continue even when budget pressures ease.
 The Pew Charitable Trusts. “Public Safety Performance Project: State Work,” http://www.pewstates.org/projects/public-safety-performance-project-328068/state-work.
 National Association of State Budget Officers, State Expenditure Report: Examining Fiscal 2010-2012 State Spending, 2012,http://www.nasbo.org/sites/default/files/State%20Expenditure%20Report_1.pdf.
 Council of State Governments Justice Center, Justice Reinvestment State Brief: Texas,2007,http://justicereinvestment.org/files/TexasStateBrief.letter.pdf.
 Council of State Governments Justice Center, Justice Reinvestment in Texas: Assessing the Impact of the 2007 Justice Reinvestment Initiative, 2009, http://justicereinvestment.org/files/Texas_Bulletin.pdf.
 State of Texas Legislative Budget Board, Statewide Criminal Justice Recidivism and Revocation Rates, January 2013,http://www.lbb.state.tx.us/Public_Safety_Criminal_Justice/RecRev_Rates/Statewide%20Criminal%20Justice%20Recidivism%20and%20Revocation%20Rates2012.pdf.
 Lauren E. Glaze and Erika Parks, Correctional Populations in the United States, 2011, U.S. Department of Justice Bulletin, November 2012, http://bjs.ojp.usdoj.gov/content/pub/pdf/cpus11.pdf.
 Public Opinion Strategies and Mellman Group, Public Opinion on Sentencing and Corrections in America, March 2012,http://www.pewstates.org/uploadedFiles/PCS_Assets/2012/PEW_NationalSurveyResearchPaper_FINAL.pdf
 Jack Leonard and Maura Dolan, “Softer 3-Strikes Law Has Defense Lawyers Preparing Case Reviews,” Los Angeles Times, November 8, 2012, http://articles.latimes.com/2012/nov/08/local/la-me-three-strikes-20121108.
 Right on Crime. “Statement of Principles,” http://www.rightoncrime.com/wp-content/uploads/2012/11/RightOnCrime-Statement-of-Principles.pdf.
 The Pew Charitable Trusts, Risk/Needs Assessment 101: Science Reveals New Tools to Manage Offenders, September 2011,http://www.pewstates.org/uploadedFiles/PCS_Assets/2011/Pew_Risk_Assessment_brief.pdf.
 The Pew Charitable Trusts, Prison Count 2010, April 2010,http://www.pewtrusts.org/uploadedFiles/wwwpewtrustsorg/Reports/sentencing_and_corrections/Prison_Count_2010.pdf.