Outside of Texas, the state of California has the largest prison population in the country, with just under 100,000 people serving time in state-run correctional facilities. That number actually represents a substantial reduction from years past, thanks in large part to a slew of state sentencing reforms. In 2006, there were as many as 165,000 California state prisoners, a population so large that federal courts mandated the state find a way to ease prison overcrowding. In 2015, California voters had their say, passing Proposition 47, a ballot measure to further reduce overcrowding by lowering penalties for nonviolent crimes like shoplifting, larceny of low-value items, and possession of small amounts of illegal drugs.
But recent data shows that most of California’s state-run adult correctional facilities still house more inmates than the facilities were designed to hold. Prison overcrowding typically requires measures like converting double-occupancy cells into triples and filling common areas like gymnasiums with bunk beds. Prison overcrowding increases the chance of violence encounters between inmates, reduces sanitary conditions, and adds more security challenges for prison staff. (Also see, California is the state with the most people on death row.)
To identify the biggest prisons in California and how crowded they are, 24/7 Wall St. reviewed inmate counts in 32 of the state’s adult correctional institutions. Data is as of March 1, 2023, as reported by the California Department of Corrections and Rehabilitation Division of Correctional Policy Research and Internal Oversight Office of Research. Inmate counts include all boarders confined in state-run prisons. All data came from the California Department of Corrections and Rehabilitation.
Out of the 32 state correctional facilities with data, only eight hold fewer inmates than the facility was designed to hold. These include the California Institution for Women in the city of Chino, east of Los Angeles, and the California State Prison in Sacramento.
At the other end of the spectrum, the state’s largest prisons by inmate populations are also among the most overcrowded. These include Avenal State Prison in the central San Joaquin Valley and the California Rehabilitation Center in Riverside County, which are run at 159% and 166% overcapacity, respectively. (Also read: California Has Had More Weather Disasters Than Any Other State in the Last Decade)
Five California state prisons, including Avenal and CRC have occupancy rates of more than 150%, meaning that the facility is holding about one extra inmate for every two it was intended to hold. The average occupancy rate for all 32 correctional facilities is 118%.
Here are California’s biggest prisons.
32. California Institution for Women (CIW)
> Inmates: 983
> Capacity: 1,281 – #32 most on list
> Percent occupied: 77% – #31 highest on list
> County: San Bernardino County
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31. California State Prison, Sacramento (SAC)
> Inmates: 1,513
> Capacity: 1,828 – #28 most on list
> Percent occupied: 83% – #28 highest on list
> County: Sacramento County
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30. Pelican Bay State Prison (PBSP)
> Inmates: 1,602
> Capacity: 2,380 – #16 most on list
> Percent occupied: 67% – #32 highest on list
> County: Del Norte
29. California Correctional Institution (CCI)
> Inmates: 1,900
> Capacity: 2,172 – #24 most on list
> Percent occupied: 88% – #26 highest on list
> County: Kern
28. California Medical Facility (CMF)
> Inmates: 1,975
> Capacity: 2,318 – #18 most on list
> Percent occupied: 85% – #27 highest on list
> County: Solano
27. Chuckawalla Valley State Prison (CVSP)
> Inmates: 2,094
> Capacity: 1,738 – #30 most on list
> Percent occupied: 121% – #14 highest on list
> County: Riverside
26. California Institution for Men (CIM)
> Inmates: 2,196
> Capacity: 1,604 – #31 most on list
> Percent occupied: 137% – #8 highest on list
> County: San Bernardino
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25. Central California Women’s Facility (CCWF)
> Inmates: 2,355
> Capacity: 1,990 – #26 most on list
> Percent occupied: 118% – #15 highest on list
> County: Madera
24. California Health Care Facility – Stockton (CHCF)
> Inmates: 2,360
> Capacity: 2,953 – #9 most on list
> Percent occupied: 80% – #30 highest on list
> County: San Joaquin
23. Calipatria State Prison (CAL)
> Inmates: 2,494
> Capacity: 2,308 – #19 most on list
> Percent occupied: 108% – #23 highest on list
> County: Imperial
22. High Desert State Prison (HDSP)
> Inmates: 2,518
> Capacity: 2,324 – #17 most on list
> Percent occupied: 108% – #22 highest on list
> County: Lassen
21. California State Prison, Los Angeles County (LAC)
> Inmates: 2,557
> Capacity: 2,300 – #22 most on list
> Percent occupied: 111% – #20 highest on list
> County: Los Angeles
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20. Centinela State Prison (CEN)
> Inmates: 2,589
> Capacity: 2,308 – #19 most on list
> Percent occupied: 112% – #19 highest on list
> County: Imperial
19. Kern Valley State Prison (KVSP)
> Inmates: 2,694
> Capacity: 2,448 – #15 most on list
> Percent occupied: 110% – #21 highest on list
> County: Kern
18. Salinas Valley State Prison (SVSP)
> Inmates: 2,900
> Capacity: 2,452 – #14 most on list
> Percent occupied: 118% – #15 highest on list
> County: Monterey
17. RJ Donovan Correctional Facility (RJD)
> Inmates: 2,938
> Capacity: 2,992 – #7 most on list
> Percent occupied: 98% – #25 highest on list
> County: San Diego
16. Pleasant Valley State Prison (PVSP)
> Inmates: 2,940
> Capacity: 2,308 – #19 most on list
> Percent occupied: 127% – #12 highest on list
> County: Fresno
15. Folsom State Prison (FOL)
> Inmates: 3,023
> Capacity: 2,065 – #25 most on list
> Percent occupied: 146% – #6 highest on list
> County: Sacramento
14. California Rehabilitation Center (CRC)
> Inmates: 3,026
> Capacity: 1,822 – #29 most on list
> Percent occupied: 166% – #1 highest on list
> County: Riverside
13. Valley State Prison (VSP)
> Inmates: 3,044
> Capacity: 1,961 – #27 most on list
> Percent occupied: 155% – #3 highest on list
> County: Madera
12. California Men’s Colony (CMC)
> Inmates: 3,161
> Capacity: 3,816 – #1 most on list
> Percent occupied: 83% – #28 highest on list
> County: San Luis Obispo
11. Ironwood State Prison (ISP)
> Inmates: 3,180
> Capacity: 2,200 – #23 most on list
> Percent occupied: 145% – #7 highest on list
> County: Riverside
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10. California State Prison, Corcoran (COR)
> Inmates: 3,284
> Capacity: 3,115 – #5 most on list
> Percent occupied: 105% – #24 highest on list
> County: Kings
9. California State Prison, Solano (SOL)
> Inmates: 3,438
> Capacity: 2,594 – #13 most on list
> Percent occupied: 133% – #9 highest on list
> County: Los Angeles
8. Mule Creek State Prison (MCSP)
> Inmates: 3,846
> Capacity: 3,284 – #4 most on list
> Percent occupied: 117% – #17 highest on list
> County: Amador
7. San Quentin State Prison (SQ)
> Inmates: 3,897
> Capacity: 3,084 – #6 most on list
> Percent occupied: 126% – #13 highest on list
> County: Marin
6. Wasco State Prison (WSP)
> Inmates: 3,951
> Capacity: 2,984 – #8 most on list
> Percent occupied: 132% – #10 highest on list
> County: Kern
5. Sierra Conservation Center (SCC)
> Inmates: 3,956
> Capacity: 3,404 – #3 most on list
> Percent occupied: 116% – #18 highest on list
> County: Tuolumne
4. North Kern State Prison (NKSP)
> Inmates: 4,153
> Capacity: 2,694 – #12 most on list
> Percent occupied: 154% – #4 highest on list
> County: Kern
3. Correctional Training Facility (CTF)
> Inmates: 4,265
> Capacity: 2,800 – #11 most on list
> Percent occupied: 152% – #5 highest on list
> County: Monterey
2. California Substance Abuse Treatment Facility (SATF)
> Inmates: 4,535
> Capacity: 3,424 – #2 most on list
> Percent occupied: 132% – #10 highest on list
> County: Kings
1. Avenal State Prison (ASP)
> Inmates: 4,612
> Capacity: 2,909 – #10 most on list
> Percent occupied: 159% – #2 highest on list
> County: Kings
Methodology
To identify the biggest prisons in California and how crowded they are, 24/7 Wall St. reviewed inmate counts in 32 of the state’s adult correctional institutions. Data is as of March 1, 2023, as California Department of Corrections and Rehabilitation Division of Correctional Policy Research and Internal Oversight Office of Research.
Inmate counts include felons, county contract boarders, federal boarders, state boarders,
safekeepers, county diagnostic cases, Department of Mental Health boarders, and Division of
Juvenile Justice boarders confined in state-run prisons. Each prison’s total capacity and occupancy also came from the California Department of Corrections and Rehabilitation.
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