What was the final straw that led to southern states to secede in the us?

The final straw that led southern states to secede from the Union was the election of Abraham Lincoln in 1860. His anti-slavery stance and the belief that he would limit the expansion of slavery into new territories caused deep concern among southern states, which relied on slavery for their agricultural economy. Following his election, several southern states seceded, viewing Lincoln's presidency as a direct threat to their rights and way of life, ultimately leading to the outbreak of the Civil War.