Where would we be if we had adopted a hemp powered hemp car? I wouldn't bang on a regular car like the video below.from what I had read it was because hemp could be used to make paper and cut into Hurst's profits in the pulp wood business.
edit:
William Randolph Hearst to the Devastating Marijuana Prohibition
William Randolf Hearst spent his life building his media empire and used it to provide a platform to the devastating marijuana prohibition.greendorphin.com