United States · Colorado · Florence
Data is aggregated from public sources and may be incomplete or out of date. Always verify with primary sources before acting on any figure. See data sources.
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The federal supermax — the highest-security prison in the US federal system. Holds inmates judged 'extreme risks' including terror convicts and prior escapees.
Capacity
490
Current population
360
Occupancy
73%
Year opened
1994
Operational
Figures from official sources · verified 20 May 2026 · methodology
Operator
Federal Bureau of PrisonsPopulation held
male
Opened
1994
Region
Colorado
Security level
Supermax
Death-row facility
No
Single-cell confinement averaging 22-23 hours per day. Cells include a concrete bed, sink-toilet, and a 4-inch window. Recreation in an individual outdoor cage.
Visits by appointment only; non-contact through plexiglass for most inmates. Approved visitor list required, processed by the warden's office.
Mail screened by staff. No polaroids, hardcover books, or staples. Address: Inmate Name & Register #, ADX Florence, PO Box 8500, Florence, CO 81226.
Inmate phone time is restricted and pre-scheduled. Money for commissary via MoneyGram or Western Union to the BOP Trust Fund.
Long-running litigation over solitary confinement of mentally ill prisoners (Cunningham v. BOP, settled 2016).
Ramzi Yousef, Ted Kaczynski (transferred 2021), Robert Hanssen, Terry Nichols, Zacarias Moussaoui.
Derived signal — not a judgement. How it's calculated
What the score is responding to:
This facility scores 5. The national average across 7,437 scored United States facilities is 2 — 3 points above national average.
Population and occupancy by year. Source: official corrections statistics + oversight reports.
Population held
Occupancy %
Same country, matched on type + security level where possible.
Higher risk than 75% of peer facilities in United States.
l Project Inside News & Awards Impact People Supporters Jobs Contact Us Investigate This! Newsletters Events Donate Feedback? [email protected] At the ADX Florence supermax prison in Colorado, the Department of Justice’s inspector general found mentally ill inmates held in solitary confinement despite a 2014 change in policy meant to improve their care. Brennan Linsley/Associated
BOP agreed to fundamental reforms in the identification and treatment of mentally ill prisoners at ADX, including the creation of two new mental-health step-down units.
ge. “You never know what to expect from a crazy person because there are so many types of crazy,” Daniel Delaney wrote in a letter to The Marshall Project. Delaney is currently at ADX Florence in Colorado for killing his cellmate in solitary in 2010 at another federal prison. “A lot of crazy people don’t shower or clean up after themselves. Some make funny noises. Some just tear out pages from
il January of last year. Dusenbury spoke with us about what life is like inside the most isolated, rarely glimpsed prison in the United States. What was your first impression of ADX Florence when you arrived there? It wasn’t like any of the prisons I’d been to, and I’ve been to a lot of prisons. I’ve been locked up in some isolated, rural places, but at least at those places I could always see a
How many of our profile fields are populated. We surface this so families and researchers know the limits.
Under CC-BY-4.0. Include the URL and access date; the site is a living reference and entries can change.
World Prisons. (2026). ADX Florence. Retrieved July 21, 2026, from https://worldprisons.com/prisons/adx-florence
"ADX Florence." World Prisons. Accessed July 21, 2026. https://worldprisons.com/prisons/adx-florence.
@misc{worldprisons-adx-florence,
author = {{World Prisons}},
title = {ADX Florence},
year = {2026},
url = {https://worldprisons.com/prisons/adx-florence},
urldate = {2026-07-21}
}