Why did Lincolns election lead to the secession of many of the Southern states?

Lincoln's election in 1860 was seen by many Southern states as a direct threat to the institution of slavery, which was integral to their economies and social order. His platform of halting the expansion of slavery into new territories alarmed Southern leaders, who feared this would ultimately lead to the abolition of slavery itself. As a result, several Southern states chose to secede from the Union, believing they needed to protect their rights and way of life. This secession ultimately contributed to the outbreak of the Civil War.