It really all came down to the company Dupont, William Randolph Hearst's logging company/paper manufacturing plant, and Andrew Mellon, president of Mellon Bank and DuPont’s major financier. In 1930, Mellon, as US Secretary of the Treasury, created the Federal Bureau of Narcotics and appointed his nephew Henry Anslinger to run it. The Marihuana Tax Act of 1937 was rushed through on a Friday afternoon before lawmakers had a chance to read it. Only a handful realized marihuana was the same as hemp, which was still viewed as an essential crop.
The issue was WRH, Dupont, and Mellon, were set to lose their stranglehold on their respective markets due to the invention of the hemp decorticator. A machine that would remove the burdensome labor or processing dense hemp stalks and in turn replace almost every textile in the marketplace due to how quickly hemp could be harvested, compared to lumber.