The Mexican-American war is to be partially blamed for the civil war for a big reason, slavery. Slavery during the American-Mexican war was very problematic concerning the North and the South. There were problems between the NOrth and South concerning if slavery should be allowed or not, the North wanted slaves to be free but the south did not. The south benefitted from the slaves because in the south cotton fields and factories were more common and they would be handled by the slaves. The slave owners also referred to as masters, would say how labor work was only for slaves and doing their work would make the masters stoop down to the slaves level. What divided the North and South more was the Fugitive Slave Act which denied a trial to fugitives.