"We calculate that a reduction by one-half in the incarceration rate of non-violent offenders would lower correctional expenditures by $16.9 billion per year and return the U.S. to about the same incarceration rate we had in 1993 (which was already high by historical standards). The large majority of these savings would accrue to financially squeezed state and local governments, amounting to about one-fourth of their annual corrections budgets. As a group, state governments could save $7.6 billion, while local governments could save $7.2 billion."
Schmitt, John; Warner, Kris and Gupta, Sarika. The High Budgetary Cost of Incarceration. Center for Economic and Policy Research. Washington, DC: June 2012.