ADX Florence is the federal supermax prison in Florence, Colorado, and the only facility of its kind in the federal system. Operated by the Bureau of Prisons as United States Penitentiary Florence Administrative Maximum, it holds inmates the government has judged too dangerous, too well-connected, or too great an escape risk for any other high-security penitentiary. Prisoners spend 22 to 24 hours a day alone in concrete cells designed to prevent contact with other inmates, communication with the outside world, or any sense of where they are on the grounds.
The facility opened in 1994 as part of the larger Federal Correctional Complex about 100 miles south of Denver. It houses several hundred male inmates at a security tier above every other federal prison.
Who Ends Up at ADX
The Bureau of Prisons reserves ADX designation for a narrow slice of the federal inmate population. The facility was built directly in response to the 1983 murders of two correctional officers at USP Marion by Aryan Brotherhood members, which exposed the limits of the existing maximum-security model. Everything about ADX was designed to isolate inmates capable of extreme violence toward staff or other prisoners, along with those whose escape would threaten national security.
Typical candidates include leaders of organized crime networks whose reach could compromise operations elsewhere, individuals convicted of domestic or international terrorism, inmates with repeated histories of assaulting staff or other prisoners, and those who have tried to escape from high-security facilities. The BOP reviews each designation periodically to confirm the custody level still fits the inmate’s current risk profile.
Inside the Cell
Every ADX inmate occupies a single cell measuring roughly seven by twelve feet. The bed, desk, and stool are poured concrete, molded directly into the structure so nothing can be removed, weaponized, or modified. A stainless steel sink-toilet combination is the only non-concrete fixture. A narrow window, about four inches wide, is angled through the thick exterior wall so the inmate cannot see other buildings, roads, or landmarks that would reveal their location within the complex.
The walls are engineered to block sound between adjacent cells, preventing conversation with neighbors. Electronic surveillance covers the living area, supplemented by pressure-sensitive pads and motion detectors along the perimeters.
Checks are constant. Unit officers visually confirm each inmate every 15 minutes through the cell-door window. Lieutenants enter each cell and physically inspect restraints every two hours. Medical staff perform checks every four hours, and mental health staff check in at least once every 24 hours.
Time Out of the Cell
Out-of-cell time varies by unit. Inmates in the general population units receive about two hours per weekday, split between indoor and outdoor recreation on a rotating basis. The outdoor areas are deep concrete enclosures with caged ceilings, where inmates occupy individual cages that allow limited visual and verbal contact with a small number of others. In the Special Housing Unit, only one inmate goes outside at a time.
At the other end of the spectrum, the least restrictive housing unit (Kilo Unit) allows up to seven hours of out-of-cell time per day, with access to a common area that includes a stationary bike. Three to five staff members escort every inmate to recreation, and officers search the cell each time the inmate leaves it. Any movement outside the cell requires an escort of at least two guards, with the inmate in handcuffs and leg irons before the door opens.
Contact With the Outside World
At the ADX specifically, all visits are conducted through glass partitions using internal telephones, with no physical contact permitted. Before anyone can visit, they have to complete a Bureau of Prisons background screening that typically takes several weeks; the inmate mails a Visitor Information form (BP-A0629) to each person they want on their approved list, and the BOP checks for security concerns or unauthorized ties to other inmates. Adult visitors must present current, unexpired government photo ID at the gate.
Phone access is limited. Most federal inmates receive 300 phone minutes per month, with each call capped at roughly 15 minutes before the line disconnects. All calls are monitored and recorded except attorney-client communications. Inmates on disciplinary status may see their minutes reduced.
The Trust Fund Limited Inmate Computer System (TRULINCS) lets inmates exchange monitored electronic messages with approved contacts, paid for in “TRU-Units” purchased from the inmate’s trust fund account. Traditional postal mail is also available, subject to inspection for contraband or coded messages. Family members can deposit funds into an inmate’s trust account through Western Union’s Quick Collect program, using the inmate’s eight-digit register number.
Special Administrative Measures
Some ADX inmates face a further layer of restriction called Special Administrative Measures, authorized under 28 C.F.R. §§ 501.2 and 501.3. The Attorney General can impose SAMs when an inmate’s communications are deemed a potential threat to national security or a possible trigger for acts of violence. The measures go well beyond ordinary ADX conditions.
Under SAMs, phone calls may be limited to one 15-minute call per month to an approved immediate family member, monitored and recorded by the FBI and conducted in English unless a government translator is available. In-person visits are restricted to one approved family member at a time, with 14 days’ written notice to the BOP. Mail is limited to three pages per week to a single recipient, copied and reviewed by the FBI before delivery. SAMs inmates are generally barred from communicating with other prisoners, praying together, or having any contact with the media. A gag order extends to the inmate’s attorney and family, prohibiting them from relaying messages from the prisoner to third parties.
The Step-Down Program
ADX is not necessarily permanent. The Bureau of Prisons runs a step-down program that gives inmates a structured path toward transfer to a less restrictive facility. It moves through four phases: general population (minimum 12 months), intermediate (minimum six months), transitional (minimum six months), and pre-transfer (minimum 12 months). The ordinary timeline runs about 36 months from start to transfer eligibility, though there is no hard maximum or minimum.
To advance, an inmate must show at least six months of clear conduct in the intermediate unit, complete recommended programs, maintain respectful behavior toward staff and other inmates, and keep acceptable personal hygiene and cell sanitation. A Step-Down Review Committee decides whether the inmate can safely function in a less restrictive setting. Inmates who are denied advancement receive a written explanation and can challenge the decision through the BOP’s administrative remedy program. Those who finish the pre-transfer phase can be moved to an appropriate lower-security federal facility.
Mental Health and the Cunningham Settlement
The extreme isolation at ADX has drawn sustained legal scrutiny over its effects on inmates with mental illness. In Cunningham v. Federal Bureau of Prisons, a class action filed on behalf of ADX inmates, the parties reached a settlement that required the BOP to make significant changes at the facility. The agreement mandated improved screening and diagnosis of mental illness for all ADX inmates, creation of group therapy facilities and private counseling areas, enhanced at-risk recreation programming, suicide prevention measures, and steps to ensure access to treatment. The BOP was also required to develop dedicated mental health treatment units at Florence and two other locations.
A court-appointed monitor oversaw compliance with the settlement terms, which remained in effect for a minimum of three years with a possible one-year extension. Advocacy groups have continued to raise concerns about whether the reforms have been fully sustained.
Challenging Placement or Conditions
Inmates who want to dispute their placement, conditions, or any aspect of their confinement can use the BOP’s Administrative Remedy Program. The process runs through four levels, each with strict deadlines:
- Informal resolution using form BP-8, which must be raised with staff and followed by the formal request within 20 calendar days of the triggering event.
- Formal request to the Warden on form BP-9. The Warden has 20 calendar days to respond, or three days if the matter is an emergency threatening the inmate’s immediate health or welfare.
- Regional appeal on form BP-10, filed with the Regional Director within 20 calendar days of the Warden’s response. The Regional Director has 30 days to respond.
- Final appeal on form BP-11 to the BOP General Counsel, filed within 30 calendar days of the Regional Director’s response. The General Counsel has 40 days to respond.
Missing any of these deadlines can effectively end the complaint. The program covers most confinement-related issues but does not apply to tort claims, accident compensation claims, Freedom of Information Act requests, or allegations of sexual abuse, which go through separate procedures. Exhausting this administrative process is generally a prerequisite before an inmate can file a federal lawsuit challenging conditions of confinement.
Who Is Held There
The ADX population includes many of the most significant federal criminal defendants of the past three decades. Current or recent inmates have included Joaquín “El Chapo” Guzmán, the Sinaloa Cartel leader serving life plus 30 years; Dzhokhar Tsarnaev, the Boston Marathon bomber under a death sentence; Terry Nichols, serving 161 consecutive life terms for the Oklahoma City bombing; and Ramzi Yousef, mastermind of the 1993 World Trade Center bombing, serving life plus 240 years.
The facility has also held Richard Reid, the “shoe bomber” serving three consecutive life terms; Zacarias Moussaoui, a 9/11 conspirator serving life without parole; and Larry Hoover, co-founder of the Gangster Disciples, serving six life terms for drug conspiracy and extortion. Two high-profile inmates died there in 2023: Ted Kaczynski, the Unabomber, and Robert Hanssen, the former FBI agent who sold classified information to Russian intelligence.