The US Dept. of Justice's Bureau of Justice Statistics reports that at yearend 2021 there were 1,021,288 sentenced people in state prisons in the US, of whom 127,348 (12.5%) had as their most serious offense a drug charge: 34,382 for drug possession (3.4%) and 92,965 for "other" drug offenses, including manufacturing and sale (9.1%).
Source
E. Ann Carson, PhD, and Rich Kluckow, DSW. Prisoners In 2022 - Statistical Tables. Washington, DC: US Dept of Justice Bureau of Justice Statistics, November 2023, NCJ307149.