The problem with weed in America is black people, black music and racism. "Darkies smoke marijuana to think they're as good as white folk." That was said of the US Senator, Harry Anslinger, who spearheaded the efforts to make pot illegal. There was also a push from the timber industry (who does have reason to fear hemp), but it's largely stigmatized because it's always been attached to black music (which, ironically, white people here can't get enough of and copy it until it's dead, but only once a white artist doing it appeals to the white masses. That's basically the story of rock n roll here).