That's a stat for Federal prisons - it's a completely different set of laws and crimes than state and local laws, and only 10% Americans incarcerated are in federal prisons.

Here's a breakdown by most serious offense for my state's prison system:

https://www.doc.sc.gov/research/InmatePopulationStats/ASOF-M...

Which has 16% drugs, but also:

26% homicide, 12% Robbery, 11% Burglary, 9.5% Rape/Sexual assault, 6.6% Kidnapping, 6.4% Assault.

I wrote an blog post a while back about how prison populations skew so much towards the most violent crimes.

http://braino.org/essays/why_so_many_people_in_prison/

Prison populations skew toward violent crimes because the sentences for them are longer. They aren't representative of the number of convicts.

>Only a little over 1/3rd are actually in prison for violent crime

On that chart, I was a little bit surprised to see the percentages for:

    - category (g) (Homicide, Aggravated Assault, and Kidnapping Offenses) and
    - category (l) (Sex Offenses) 

...are as high as they are (although probably not that high in absolute numbers) for federal prison. I wonder where one could find a breakdown of the offenses? I'd have thought the only way to get a federal rape or murder sentence would be to commit the act on an FBI agent or other on-duty federal agent (Secret Service, US Marshals, Postman, others?). But I guess maybe soldiers who have been court-martialed end up in federal prison? That might explain most of those? And maybe kidnapping becomes a federal offense if you cross state lines?

That table looks like it sums to 100%, which is confusing. Many prisoners have been convicted of both drug and weapons charges. How is that represented?

My understanding is that while the rate of prisoners with drug charges is high, the rate of prisoners with only drug charges is a lot lower.