The biggest prison in the US depends on how you measure it. By land area, it’s the Louisiana State Penitentiary, known as Angola, which covers 18,000 acres in West Feliciana Parish, Louisiana.1Louisiana Department of Public Safety & Corrections. Louisiana State Penitentiary By population, the largest correctional facility is the Los Angeles County Jail system, which held an average daily population of 12,738 people during the first quarter of 2025.2Los Angeles County Sheriff’s Department. Custody Division Population Quarterly Report – First Quarter 2025 Both titles are accurate, because they describe different kinds of facilities.
Prison or Jail? The Distinction Matters
Prisons and jails aren’t the same thing, even though the words get swapped around in everyday speech. Jails are local facilities run by cities or counties that hold people awaiting trial or serving short sentences, usually under one year. Prisons are state or federal institutions where people serve longer sentences after conviction. That difference is why Angola and the LA County Jail can both claim to be the “biggest” without one answer canceling out the other. Angola is the largest single prison. LA County runs the largest jail operation.
Across the country, nearly two million people are incarcerated in more than 6,000 facilities, including state prisons, federal institutions, local jails, juvenile centers, and immigration detention sites. The biggest individual facilities sit at the top of a very large pyramid.
Louisiana State Penitentiary: Biggest by Land Area
Angola occupies 18,000 acres of former plantation land, making it physically larger than the dry-land area of Manhattan, which covers roughly 14,700 acres. The Mississippi River curves around three sides of the property, forming a natural boundary that functions as part of the security perimeter. The fourth side is rural Louisiana terrain. Geography does a lot of the work that walls do at other prisons.
It’s also the largest maximum-security prison in the country, holding approximately 5,000 incarcerated people with around 1,800 staff members.3Wikipedia. Louisiana State Penitentiary Rather than a single building, Angola operates as a set of camps and housing units spread across the property, connected by an internal road network that moves staff, supplies, and inmates between locations. It functions less like a building and more like a small locked-down town.
A Working Farm
Most of Angola’s acreage is farmland. Incarcerated workers cultivate wheat, corn, soybeans, cotton, and milo across the grounds, and the prison still operates as a working agricultural enterprise, with crops and livestock helping offset institutional costs. The land also includes forests and grazing areas that require their own maintenance.
The agricultural model goes back to the facility’s origins. The land was a plantation worked by enslaved people before the Civil War, and the name “Angola” comes from the country of origin of many of those workers. After emancipation, Louisiana turned to convict leasing to keep cheap labor on the same ground.4Law Library of Louisiana. Locked Up: A Historical Look at Incarceration in New Orleans and Louisiana – Angola, West Feliciana Parish The state eventually took direct control and formalized Angola as a state-run penitentiary, but the agricultural labor model carried over.
Wages for that labor remain contested. Incarcerated workers in Louisiana earn pennies per hour for agricultural work, sometimes nothing at all. Critics draw a direct line between the current system and the plantation economy that preceded it. Supporters argue the farm work provides structure during long sentences and teaches employable skills.
Life Sentences and an Aging Population
Angola holds one of the highest concentrations of people serving life sentences of any facility in the country. A large majority are serving life without parole, often under Louisiana’s historically aggressive sentencing laws. The population ages in place, which means Angola operates partly as a geriatric and hospice care facility, delivering long-term medical treatment to people who will never be released.
Los Angeles County Jail: Biggest by Population
The Los Angeles County Jail system is the largest jail operation in the United States and one of the largest in the world, running nine separate facilities across the county.5Los Angeles Almanac. County Correction Facilities and Jails Its first-quarter 2025 average daily population of 12,738 was above its rated capacity of 12,404. That gap, however narrow, is what drives much of the system’s legal and political pressure.
The best-known components are the Twin Towers Correctional Facility and Men’s Central Jail. Twin Towers functions as one of the largest de facto mental health facilities in the country, because jails have become a default destination for people with serious behavioral health conditions who end up in the criminal justice system. Men’s Central Jail is an aging, overcrowded building that has been the subject of closure and replacement debates since at least 2018. The county has floated multiple plans, including a $2.2 billion replacement facility and a $1.7 billion mental health treatment center, but none have been built. As of late 2024, county supervisors appeared to be stepping back from a complete closure strategy.
Why the Population Churns
Most people in the LA County Jail haven’t been convicted of anything. They’re pretrial detainees waiting for court dates, unable to post bail, or moving through the early stages of their cases. The system processes an enormous number of bookings and releases every day, far more than any single prison. That churn is what distinguishes a massive jail from a massive prison like Angola, where the population is relatively stable and serving defined sentences.
Operating above rated capacity isn’t just an operational problem. Overcrowded jails attract federal lawsuits, consent decrees, and court-ordered population caps. LA County has invested in diversion programs, including a Rapid Diversion Program created in 2019 and a Jail Population Review Council launched in 2020, both aimed at identifying people who can be safely released or routed into treatment. The programs have made a measurable dent, but the jail population remains stubbornly above capacity.
Federal Correctional Complex Coleman: Biggest Federal Facility
The federal system is structured differently. Federal Correctional Complexes group multiple institutions at different security levels on a single site, sharing staff, services, and emergency resources.6Federal Bureau of Prisons. Federal Prisons The Federal Correctional Complex in Coleman, Florida, is the largest, with four separate facilities: two high-security U.S. penitentiaries (Coleman I and Coleman II), a medium-security institution, and a low-security institution.7Federal Bureau of Prisons. FCI Coleman Medium
Bureau of Prisons data shows Coleman Low holding roughly 1,600 inmates and Coleman Medium holding approximately 1,550, with the two high-security penitentiaries adding significantly more.8Federal Bureau of Prisons. Population Statistics Combined across all four facilities, Coleman holds the largest concentration of federal inmates in the country. The federal system overall holds about 154,000 people, a fraction of the roughly two million total incarcerated nationwide.
Other Large Facilities Worth Knowing
Rikers Island in New York City has long been one of the most infamous jail complexes in the country. The city has committed to closing it by the end of 2026 and replacing it with smaller, borough-based facilities, targeting a jail population of approximately 3,300.9New York City Council. Rikers to Close That’s a dramatic reduction from the tens of thousands Rikers held at its peak decades ago.
Texas operates one of the largest state prison systems in the country, with dozens of units spread across the state. Several individual Texas units hold thousands of inmates each, and the system as a whole incarcerates well over 100,000 people. No single Texas facility matches Angola’s acreage or the LA County Jail’s daily population, but the combined scale of the Texas system is rivaled only by California’s.