The hemp used in fabric and ropes and such is a cousin to the hemp that is smoked recreationally (it has much longer fibers than its cousin.) The cotton industry, as well as other industries, muddied the waters because they didn't want the competition, since hemp had such a wide variety of uses, grew faster, was hardy, etc. In fact, if memory serves, the whole making marijuana illegal movement was started because of this - led by, I believe, William Randolph Hearst.