by ButterflyEffect

The research wing of the U.S. Congress is warning that three decades of “historically unprecedented” build-up in the number of prisoners incarcerated in the United States have led to a level of overcrowding that is now “taking a toll on the infrastructure” of the federal prison system.

There are three main things that resulted in this drastic increase. One is Richard Nixon's declaration of "the war on drugs", and the another is allowing prisoners to be hired for certain tasks. The latter was allowed starting in 1979. The third is mentioned in the article and that is mandatory minimums for sentencing. It will be interesting to see if the numbers continue to rise and what will happen to the infrastructure of the system.