How did the invention of the cotton gin in 1793 affect the use of slave labor in the south? although the cotton gin affected the tasks performed by enslaved workers, the number of workers needed remained constant. although the cotton gin did not alter the tasks performed by enslaved workers, the number of workers sharply increased. because the cotton gin was so efficient, plantation owners needed fewer enslaved workers to produce cotton. because the cotton gin processed cotton so quickly, farmers needed increasing numbers of enslaved workers.