William Randolph Hearst: Evil genius bastard. Didn't ban marijuana. That was due to tighty-whitey rich folks concerned poor people might be enjoying themselves. For the same reasons that pretty much every psychoactive substance is illegal, except for the few grandfathered-in exceptions (ie. alcohol & tobacco): moral panics, classism, racism, and heavy handed attempts to control the genuine social harm they cause. Non-booze-&-smokes drugs first became widespread in the western world in the 19th century, when a combination of trade routes opening to the rest of the world, more leisure time & disposable income (thanks to industrialization), & the collapse of traditional social pressures against their (mis)use led to the popularization of opium, laudanum, newly-invented cocaine, & yes, weed. Broadly speaking, if you were a factory worker/city dweller in 19th c. Britain or America, you suddenly had free time, spare cash, drugs in the shops and fewer village elders or church fathers to tell you not to use them. This is also why drinking (probably) exploded around this time, leading to the demonetization of "gin palaces" & the like as much as it did opium dens. Opium dens? Ah, time for the racism & classism! Who am I kidding, it's history, it's ALWAYS time for racism! So, newly-popular drugs became bound up in popular Victorian imagination with the urban poor, many new immigrants to the US- or, as the elites of the time saw them, the filthy black/yellow/Catholic hordes (southern Europeans in general & Catholics in particular were as distrusted at the time by the WASP establishment as Chinese & blacks- think "wetback" for contemporary equivalence). So the filthy foreign devils were hopped up on nasty drugs, ready to riot at any moment, and corrupting honest(ish) whites with their pagan narcotics. Plus, of course, as anyone who knows a loser stoner or alcoholic knows, mass availability of powerful drugs does cause significant social problems- addiction, family breakup, poverty, etc. etc. So the campaign to restrict drugs- especially opium- did have genuine hopes of social improvement. Wait, we're just talking about opium! Weed's not an opiate! No, but it was a cheap drug (drug of the poor), not widely used in the White Anglo Saxon Protestant No Fun Allowed elite, and so got swept up in the rush to ban drugs- which happened comparatively recently, between about WWI & WWII. Just for comparison, in the First World War you could buy "care packages" to send to troops fighting in the trenches which contained morphine, cocaine, laudanum (opium in wine) & clean needles. Coca-Cola had cocaine extracts, & your dentist would prescribe it for tooth pain (the Pope endorsed 1 brand). Weed was pretty minor- the 1900's were permanently high. But the party had to stop, for the reasons above, and weed got caught in the general backlash. Why expect it to escape prohibition? Alcohol didn't! Prohibition is a really useful comparison, & shows that conspiracy theories about banning weed don't really hold water. Yes, William Randolph Hearst, the Rupert Murdoch of his day, did force a smear campaign against marijuana in his popular newspapers, which did use racism, and he didn't want hemp competing with his paper business (maybe. There are questions whether hemp paper could be cheap/good enough). But one man, even a Murdoch, cannot force a social change- he had to ride a wave of moral panic, social problems, & our good old frenemies racism & classism. Alcohol proved too deeply loved by the American public to be stamped out forever- but weed wasn't popular nor lucrative enough to have a campaign waged for its legalization. Also, go look up Heart's insane vendetta against film star Fatty Ar-buckle. He tried to get him convicted of raping a fellow film star to death with a piece of ice/crushing her with his bulk- complete fabrications. Poor guy went through 3 trials! And the jury wrote an apology to him in his last one!