text: Many say States Rights and Slavery.  The 'States Rights' answer stems from the fact that the Southern states refused to accept Federal interference with their self government.  The 'Slavery' answer stems from the fact that the particular conflict involving States rights versus Federal, in this case, was slavery.  While both are good answers, the root cause of both conflicts stems from economic pressures.  The newly invented Cotton gin provided significant financial benefits from a slave based cotton economy.  So one might suggest that Eli Whitney caused the American Civil War, when he made cotton such a lucrative venture.