Illinois

The Illinois Department of Corrections (IDOC) runs the state’s prison system — roughly 27 adult prisons, all state-operated. Illinois has prohibited the for-profit operation of prisons since 1990, so there are no private prisons in the system. Together the prisons hold around 29,000 people. IDOC’s materials refer to individuals in custody; this site uses neutral terms.

Where a person is held turns first on the sentence. A person sentenced to state prison is held in an IDOC facility; people awaiting trial or serving a jail sentence are held in a county jail (such as Cook County Jail in Chicago), which is run by the county, sets its own rules, and is not in the IDOC search.

Newly committed people are processed at a reception and classification center first — men at the Northern Reception and Classification Center (NRC), near Joliet, and women at Logan Correctional Center, in Lincoln — before assignment and transfer to a permanent prison. Illinois abolished the death penalty in 2011, so there is no death row and no execution chamber.

Two long-running facilities are changing. The historic Stateville Correctional Center maximum-security prison was emptied and effectively closed in early 2025 (the state has announced a rebuild on the same site), though the reception center on its campus continues to operate; the women’s prison at Logan has been slated to relocate to a new facility in the years ahead. Because these plans are still in motion, confirm on the locator where a person is actually held before traveling.

To find where someone is held, use the IDOC Individual in Custody Search by name or IDOC number; it covers people in IDOC custody, not county-jail detainees. Under a 2025 change, Illinois began scanning incoming personal mail and delivering copies rather than the original letters — confirm the current mailing address and format with IDOC before sending, since the system is recent (see the mail guide). Use the guides below for the statewide rules at Illinois prisons, or go straight to a specific facility.