"Correctional authorities spent $38.2 billion to maintain the Nation?'s State correctional systems in fiscal year 2001, including $29.5 billion specifically for adult correctional facilities. Day-to-day operating expenses totaled $28.4 billion, and capital outlays for land, new building, and renovations, $1.1 billion.
"The average annual operating cost per State inmate in 2001 was $22,650, or $62.05 per day. Among facilities operated by the Federal Bureau of Prisons, it was $22,632 per inmate, or $62.01 per day."

Source

Stephan, James J., "State Prison Expenditures, 2001," Bureau of Justice Statistics (Washington, DC: US Department of Justice, June, 2004), p. 1.
http://www.bjs.gov/content/pu…