Not exactly. Legal restrictions by states started in 1906. By the mid-30s it was regulated or prohibited as a drug in every state. A 1937 Act made possession or sale a federal crime, for other than medicinal reasons.
They didn't exactly make posession a crime. Hemp was still being grown as a commodity crop. The Marijuana Tax Act was presented to Congress as a tax on production. You were supposed to buy tax stamps according to how much you grew. You had to bring it in to have it weighed to buy the stamps, but if you did they wouldn't sell you the stamps. They just arrested you for posession of marijuana that didn't have the stamps.
You’re probably right. I was writing based simply on memory.