The Washington Post
MANY ARE KEPT in their cells for at least 23 hours a day with minimal contact with other people, including guards. Food is delivered through a slit in the door, and most are prohibited from attending classes or counseling sessions with other inmates.
At one time shunned in the United States, solitary confinement is becoming a tool increasingly used by corrections officials trying desperately to keep order in grossly overcrowded and sometimes chaotic prisons. These decisions are made even though solitary confinement costs roughly twice as much as keeping an inmate in the general prison population. At any given time, experts estimate that 25,000 to 100,000 prisoners are kept in some sort of "special housing unit" where they are isolated and kept apart from the general prison population. The number changes frequently as new prisoners are sent in and others sent out of solitary.