The economic and social difference between the North and the South. The South would make the raw cotton and the North would buy and use it to make goods.
States versus federal rights: two camps argued over whether state rights or federal rights were more important, thus the US Constitution was born, When nullification wouldn't work the states felt that they weren't respected and succeeded.
The fight between Slave and Non-Slave State Proponents: America be an to expand and gained the Louisiana Purchase, The Missouri Compromise passed in 1820 made a rule to prohibit slavery in states of the Louisiana Purchase
Growth of the Abolition Movement: The northerners became more polarized against slavery, this occurred after the publishing of uncle toms cabin, the Dred Scott case, john brown's raid and the passage of the fugitive slave act.
The election of Abraham Lincoln: Lincoln was elected in 1860 , they believed Lincoln was anti-slavery and in favor of Northern Intrest causing more states to su seceded