Final answer:
Lincoln's election as president in 1860 led to southern states seceding from the Union.
Step-by-step explanation:
One effect of Lincoln's election as president in 1860 was that southern states began seceding from the Union. The election of Lincoln, who opposed the expansion of slavery, was seen as a threat to the economic and social structure of the southern states that heavily relied on slavery. Several southern states, including South Carolina, Georgia, and Mississippi, seceded from the Union in response to Lincoln's victory, leading to the eventual formation of the Confederate States of America and the outbreak of the Civil War.
Learn more about Effects of Lincoln's election in 1860