Reefer Madness was spot on…and pretty well made for the 1930s
Was it a "gateway drug"? Well just about everybody I knew back then smoked, but in the ten+ years I lived in Cambridge I never even met a smack user, despite being a semi-pro musician. Acid, yeah. Maybe a few tried speed, but the vast majority never did. Worst long-term effect was that it seemed to encourage some people to become slackers.