Many of those incarcerated in the United States today are mentally ill. In fact, there are far more people with severe mental illness in prisons than in hospitals.

Correctional facilities housed 356,268 inmates with severe mental illness as of 2012, according to a report from the nonprofit Treatment Advocacy Center. Psychiatric hospitals, on the other hand, housed only 35,000 patients, a tenth as many as are in prison.

In all of the states except six—Washington, Wyoming, North Dakota, South Dakota, Kansas and New Jersey— correctional facilities hold more individuals with serious mental illness than the largest remaining state hospital.

The Treatment Advocacy Center says the decision to turn prisons into de facto mental wards has cost governments substantial sums of money.

In 2009 it cost Washington state about $30,000 to house the average, non-mentally ill prisoner. But it cost more than three times as much, more than $100,000 a year, to lock up those suffering serious mental illness. Part of that is attributable to the mentally ill spending longer in prison because of rule violations and their inability to make bail.

In Orange County, Florida, the average stay of inmates is 26 days, unless they’re mentally ill, in which case the average jumps to 51 days. At Rikers Island jail in New York, the disparity is much greater: 42 days for non-mentally ill, 215 for those who are.

One solution for reducing the number of people with mental health problems in prisons and jails would be to expand Assisted Outpatient Treatment (AOT), according to the center. AOT programs allow judges to let the mentally ill to remain in their communities, as long as they keep taking their medication. If they fail to do so, the offenders can be involuntarily committed.

A pilot project in Nevada County, California, reduced jail time for mentally ill people from 521 days to 17, according to Mother Jones. Likewise, a North Carolina study showed AOT cut arrests of mentally ill from 45% to 12%.

Mentally ill Americans were routinely thrown together with prisoners until the mid-19th century, when reformer Dorothea Dix began a movement to create state hospitals for the mentally ill. The number of institutionalized mentally ill peaked at about 560,000 in the mid-1960s, but had dropped to 130,000 in 1980.

-Noel Brinkerhoff, Steve Straehley

To Learn More:

Summary of Findings (Treatment Advocacy Center)

There Are 10 Times More Mentally Ill People Behind Bars Than in State Hospitals (by Stephanie Mencimer, Mother Jones)

The Treatment of Persons with Mental Illness in Prisons and Jails: A State Survey (Treatment Advocacy Center) (pdf)

2 Million Mentally Ill Americans per Year Are Put in Prisons Rather than Mental Hospitals (by Noel Brinkerhoff and Danny Biederman, AllGov)

Which States Have Cut Treatment For the Mentally Ill the Most? (by Deanna Pan, Mother Jones)

Rate of Patients in Psychiatric Hospitals has Fallen to Level of 1850 (by Matt Bewig, AllGov)

Timeline: Treatments for Mental Illness (American Experience, PBS)