Unlock the Box in New Folsom ASU
I'm writing in response to your Unlock the Box survey. in my 22 years of incarceration in California prisons I've spent over 13 years in control units.
While I cannot provide accurate statistical analysis that you request, or much historical background concerning some of these control units, I can at least tell you my personal observations from first hand experience.
California State Prison - Sacramento (aka New Folsom) Administrative Segregation Unit (ASU): I was first placed in this ASU in September 1991 for "inciting" (i.e. participation in an institution food strike protest by writing to the ACLU). The ASU back then consisted of A-facility, housing units 5,6, and 7 (with 8 sometimes used as overflow), with 64 cells in each unit at double cell capacity (except in isolated cases of "single cell" status).
I would say at least 50% of the control unit was, and usually is in any control unit, Latino, the other 50% is divided by varying degrees between Afrikans and Europeans, with a small percentage of "others" (i.e. Native American, Asian, Pacific Islander, etc.). The most common reasons for ASU placement include assault on other inmates or staff, drug possession or trafficking, gang affiliation, enemy or safety concerns, weapons possession, or conspiracy investigations. Sometimes inmates are sent to ASU based on bogus confidential information or some other fabricated reason as a form of retaliation by prison officials.
As far as I know, this unit was first opened in 1985 or 86 as a Security Housing Unit (SHU) during the statewide crackdown on prison gangs. It has since been expanded to include a psychiatric Services Unit (PSU) in housing units 1-4 and a stand alone ASU building behind B-facility, with ASU-EOP in A-5, and ASU-CCCMS in B-4.
The state has recently implemented new control units in some prisons called the Behavioral Modification Unit (BMU), which I don't have much information on at this time. Additionally, most level 4 prisons have built separate "stand alone ASU" facilities which are modeled after Pelican Bay SHU to impose maximum sensory deprivation. In fact, these control units are worse than Pelican Bay SHU because of the deprivation of inmates televisions.