Yep, here is an infographic showing the breakdown of those incarcerated on drug offenses. Most are in local jails, then state prisons, then federal prisons.

Federal prisons may have the highest proportion, but they have the lowest amount of people total in them for drug uses.

One in 5 people who are incarcerated are incarcerated on drug offenses. While it may not be the 45% percent of federal prisons, it’s still hundreds of thousands of people, and you could still make the argument that drug users are flooding prisons, (as one of the above comments claimed was not the case) depending on what you think flooding means.

This is the most comprehensive thing ever with even more really good graphics.