The length of prison sentence varies by kind of crime committed, so we should note the critical distinction between stock and flow when comparing drug offenders to violent offenders:
As of 2009, the median incarceration time at state facilities for drug offenses was 14 months, exactly half the time for violent crimes. Those convicted of murder served terms of roughly 10 times greater length.
The picture is clear: Drug crimes have been the predominant reason for new admissions into state and federal prisons in recent decades. In every year from 1993 to 2009, more people were admitted for drug crimes than violent crimes. In the 2000s, the flow of incarceration for drug crimes exceeded admissions for property crimes each year. Nearly one-third of total prison admissions over this period were for drug crimes.
Violent crimes account for nearly half the prison population at any given time; and drug crimes only one fifth. But drug crimes account for more of the total number of admissions in recent years — almost one third (31 percent), while violent crimes account for one quarter:
