In 2020, law enforcement agencies in the US made an estimated 7,632,473 arrests for all offenses, of which 1,155,610 were drug arrests.

Although the intent of a 'War on Drugs' may have been to target drug smugglers and 'King Pins,' of the 1,155,610 arrests for drug law violations in 2020, 86.7% (1,001,914) were for mere possession of a controlled substance. Only 13.3% (153,696) were for the sale or manufacturing of a drug. Further, 30.3% of drug arrests in 2020 were for marijuana offenses -- a total of 350,150. Of those, an estimated 317,793 arrests (27.5% of all drug arrests) were for marijuana possession alone. By contrast in 2000, a total of 734,497 Americans were arrested for marijuana offenses, of which 646,042 (40.9%) were for possession alone.

Table: Total Annual Arrests in the US by Year and Type of Offense, 1996-2020

Source

FBI Uniform Crime Report. Crime in the United States 2020 - Arrests and Arrest Table: Arrests for Drug Abuse Violations. Washington, DC: US Dept. of Justice, September 2021.
"Crime in the United States - 2000," FBI Uniform Crime Reports (Washington, DC: US Government Printing Office, 2001), p. 216, Tables 29 and 4.1.