Carding cotton with these cards was the time consuming manual labor that Eli Whitney's cotton gin replaced. The gin made the expansion of cotton farming possible, and had a lot to do with the growth of slavery and the desire of Southerners to expand it into the west, where they wanted to raise more cotton. Cotton ruined land in those days, and it was necessary to continue opening new growing areas. As an interesting side note, Whitney was a Northerner; he had a lot to do with some of the causes of the war, whether he meant to or not. As a boy, I helped my uncle raise cotton. It was damned hard work, because you have to chop the weeds back to let it grow, then drag a long cotton sack behind you as you picked the cotton bolls by hand. Of course, this is all done by machinery now. Uncle Cash only had about forty acres, so machinery was not an option, even if he could have afforded it. He used mules to plow it, and, in season, to grind sugar cane and make sorhum mollasses. Stan