In 2016, there were 2.2 million in prison. 
In 2016, 64,000 people died from drug overdose, with Opioid and Heroin epidemics, nation wide.
Non violent drug offenders should be either released or given an opportunity to clean up and fly straight for an early release.
The basic plan is to create the Green Corps, a volunteer corps of the US Army.
Prisoners get "boot camp" indoctrination on being a good citizen, and used for various purpose, one of which is promoting green peace.
Prisoners get reduced sentences for good behavior and earn a very modest wage for services for use when released.

Jailhouse Rock

Depopulate the Prisons and Enhance Green Peace.