Legal history of cannabis in the United States
In the United States, regulation on the use, sale, and labeling of cannabis (legal term marijuana or marihuana) began at the state level in the early 20th century, and outright prohibitions began in the 1920s. By the mid-1930s, cannabis was regulated as a drug in every state, including 35 states that adopted the Uniform State Narcotic Drug Act.
Source: Wikipedia — Legal history of cannabis in the United States (CC BY-SA 4.0)