The US Dept. of Justice's Bureau of Justice Statistics reported that on Sept. 30, 2022, there were a total of 143,644 sentenced people in federal prisons in the US. Of those, 65,976 people (45.9% of the total) had as their most serious charge a drug offense. According to BJS, that figure "Includes trafficking, possession, and other drug offenses."

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.