I thought it was made illegal because the Mexican migrant workers brought it to the U.S. and corporate influence along with a very racist media campaign convinced folks that the dirty Mexicans are corrupting our kids - besides their not as productive when they're stoned.

The biggest reason for this burial was that in the 1930's Dupont obtained patents from making nylon from coal, paper from trees and plastic from oil, and didn't want to see hemp as a potential competitor. Remarkably but not surprisingly, the companies chief financial backer at the time, Andre Mellon, owned large swathes of timber land and oil. Mellon appointed his nephew-in-law Harry Anslinger to the Federal Bureau of Narcotics while other Dupont backers such as the Hearst newspaper group began to influence public opinion towards the perceived evils of marijuana. This also saw the rise of the pulp fiction novels with wonderfully lurid covers and titles such as 'I was a slave to marijuana' and films such as Reefer Madness. Basically this propaganda strategy worked and in 1937 Congress outlawed hemp. The actual science was buried, and the fact industrial hemp has such a low THC content that you would be better off smoking bananas was quietly hushed in order to confuse the public. Not only did the probation of hemp protect Du Pont but also many other corporations such as Dow and Monsanto - all of whom had vested interests in ensuring hemp industries didn't see the light of day. Another twist in the tail and 'would you believe it' factoid: car manufacturer Henry Ford grew hemp on his estate to experiment with methanol production and both he and Rudolph Diesel (diesel inventor) predicted by the end of the millennium cars would be running on hemp. Hemp production briefly re-emerged in 1942 when the federal government encouraged American farmers to grow it for the war effort.