It wasn't long after that marijuana became a target. The following is quoted without permission from "Marijuana in America: A Scientific Confrontation" by Dr. William D. Drake Jr.:
Harry Anslinger was placed in charge of the Treasury Department's finger-in-the-dike operation to halt liquor smuggling in 1926. Also, in 1926, not by coincidence, the first anti-marijuana stories began to appear in mass-circulation newspapers, and the yellow press had a lot of fun trying out marijuana's front-page possibilities.
Mr. Anslinger, with the help of a few of his powerful friends, had started a smear campaign against cannabis that rivals the Nazi smear campaigns against the Jews in post-WWII Germany. The very name marijuana (or marihuana) was introduced at this time to make it sound Mexican--some interests didn't even realize that marijuana and hemp were the same plant. His campaign resulted in stories like this:
"...under marijuana, Mexicans became "very violent, especially when they become angry and will attack an officer even if a gun is drawn on him. They seem to have no fear. I have also noted that under the influence of this weed they have enormous strength and that it will take several men to handle one man while under ordinary circumstances one man could handle him with ease." Quoted in Ernest L. Abel, Marihuana: The First 12,000 Years, p. 207
Click Here for another example of Harry Anslinger's "information".
Congressional testimony from Mr. Anslinger.
Whether or not the Treasury Department simulated those first scare stories is a moot point. What did happen is that as a result of this "anti-marijuana" drive, the first local legislation against marijuana was passed in New Orleans.
Moreover, Harry Anslinger and the anti-alcohol police bureaus, without authorization and exceeding their statutory authority, began circularizing sympathetic newspaper reprints of such stories. As anti-marijuana press campaigns spread, more and more local legislation was enacted to "protect the citizenry". By the time Prohibition drew to a close, an awareness of the 'new drug menace' had been generated among the people, and the Treasury responded in 1930 by creating a special Bureau of Narcotics. Harry Anslinger was appointed as commissioner.
Rather than expose their backsides by lobbying directly in Congress for anti-marijuana legislation--an approach which could be looked upon as a power grab by their jealous competitors among federal agencies--the narcotics bureau simply stimulated the growth of local-level anti-marijuana legislation, and then, about 1935, began pointing out the need for unifying legislation on the federal level. Within two years the bureau was home free:
"Faced with a steadily decreasing budget, the Bureau responded as any organization might react: it tried to appear more necessary, and it tried to increase its scope of operations. As a result of this response, the Marihuana Tax Act of 1937 was passed." The FBN and marihuana -- Dickson, Bureaucracy and morality, "Social Problems" (1968), pp. 152-155.
And so marijuana prohibition was born...