Census of Facilities
The Bureau of Justice Statistics has just released the 2005 Census of Federal and State Correctional Facilities. The document has a wealth of data across all States, including the numbers of privately-operated facilities.
The document can be accessed from the Basic Stats list at the top right sidebar.
Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Federal Systems, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Private Prisons, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, Wyoming