Sentenced People In State Prisons In The US Whose Most Serious Offense Was Drug Possession

The US Dept. of Justice's Bureau of Justice Statistics reports that at yearend 2018 there were 1,249,700 sentenced people in state prisons in the US, of whom 176,300 (14.1%) had as their most serious offense a drug charge: 46,500 for drug possession (3.7%) and 129,900 for "other" drug offenses, including manufacturing and sale (10.4%).

Source: 

E. Ann Carson, PhD. Prisoners In 2019. Washington, DC: US Dept of Justice Bureau of Justice Statistics, October 2020, NCJ255155.