-found it.
https://www.bop.gov/about/statistics/statistics_inmate_offen...
46% drug offenses, 6.8% immigration and we’re already past the 50% mark. That as they say, is a majority.
Edit: Looking at all populations state, federal, local yields: https://www.prisonpolicy.org/reports/pie2018.html
Note: But the offense data oversimplifies how people interact with the criminal justice system. A person in prison for multiple offenses is reported only for the most serious offense so, for example, there are people in prison for “violent” offenses who might have also been convicted of a drug offense. Further, almost all convictions are the result of plea bargains, where people plead guilty to a lesser offense, perhaps of a different category or one that they may not have actually committed.
https://fivethirtyeight.com/features/releasing-drug-offender...
> According to the Bureau of Prisons, there are 207,847 people incarcerated in federal prisons. Roughly half (48.6 percent) are in for drug offenses.
Additionally, the words "Bureau of Prisons" are actually a link to the same site GW150914 is citing (https://bop.gov/about/statistics/).
I don't believe this is true.