About the Blacks per Housing Unit map
To see what data, tools, and people's help I used to generate
the census tract maps that form the "underlayer" of this map, see the
credits page.
For the markers, I got information from many sources: the
and sometimes I just looked at maps to figure out what was there. For example, California State
University branches at Fresno and Long Beach both have high blacks per housing unit (yay!), and the normal
Google Maps showed that. I also show a few military bases which have a high blacks per housing unit value.
Census tracts are designed to have about 3,000 people in them. The tracts are adjusted every census year, but
I suspect they use the previous census' date to determine the tracts. Thus if a prison was opened in
1995, the tract might contain the prisons' inmates plus 3,000-ish locals. That would drop the blacks per
housing unit ratio. These prisons opened after 1980:
| Kern Valley | 2005 |
| Substance Abuse Treatment Facility and State Prison | 1997 |
| Salinas Valley | 1996 |
| Valley State Prison for Women | 1995 |
| High Desert | 1995 |
| Pleasant Valley | 1994 |
| Ironwood | 1994 |
| California State Prison - Los Angeles | 1993 |
| Centinela | 1993 |
| North Kern | 1993 |
| Calipatria | 1992 |
| Wasco State Prison | 1992 |
| Central California Women's Facility | 1990 |
| Pelican Bay | 1989 |
| Chuckawalla | 1988 |
| California State Prison - Corcoran | 1988 |
| Avenal | 1987 |
| Mule Creek | 1987 |
| R.J. Donovan | 1987 |
| California State Prison - Sacramento | 1986 |
| California State Prison - Solano | 1984 |
Why so many prisons in the past twenty-five years? I am guessing that partly it is due to stricter drug
laws; partly it is due to the state mental hospitals being shut down in the late 1970s; partly
it is due to California's "three strikes" law.
Some prisons appear to have lost their census forms. The census bureau does depend on the
admin people at the jail to fill out the forms so sometimes the info is suspect. You would think
that the State would care a lot about getting the count in, since there are a LOT of people in
California prisons, and House of Representatives seats are based on population.
Federal prisons don't seem to
distort the local demographics like state prisons do; the
Avenal Prison, the
Correctional Training Institude and Salinas Valley State Prison are in tracts with only prisons, and the census
data says that there is basically nobody in those tracts. (That is why they are dark grey.)
California state prisons (used to?) segregate by cell for the first three months based on race, as this
2004 Washington Post
article reports. That was challenged, and in 2005, there was a
Supreme Court decision that made it more likely that that practice would be stopped -- but I
don't know if that practice has been overturned or not.
If they put different races in different prisons, that would skew the
California prisons' demographics. Federal prisons do not segregate, even temporarily.
I figured out the latitude and longitude for all the markers by eye.
Big prisons are frequently really obvious in the aerial images:
they are in the middle of nowhere, are big buildings (frequently in a repeating pattern),
don't have trees around them, and have a big wall around them (sometimes visible by a shadow), and
frequently have a road around them. Perhaps most tellingly, they do not have a big parking lot nearby.
While the regular state and federal prisons are very large -- usually having between 2,000 and 4,000
inmates -- the Community Correctional Facilities are quite small. CCFs usually have fewer than 500
people in them, and they are hard to find on the aerial photos. I almost didn't include them on
my map because they don't really distort the local demographics enough to show up on the census map.
If you are interested in learning more about U.S. prison statistics, see the
Bureau
of Justice Statistics.
Ducky Sherwood
