According to the New York Times, it costs an average of $31,286 per year to keep a prisoner in prison as of August 2013. The cost varies depending on the state or municipality. Indiana spent $14,823 per inmate in 2012, while New York City paid $167,731 per prisoner in 2013.
The Vera Institute of Justice surveyed 40 states and found it cost them a total of $39 billion to keep prisoners in prison in 2010. According to CBS News, the United States has 25 percent of the world's prison population, more than any other country on Earth. Nationwide, as of 2012, there were almost 2.5 million Americans behind bars.