While the North relied predominately on factories and industrialization, the South maintained an agriculture-based economy and used slaves as free labor. As abolitionists continued to fight for an end to slavery, the South felt a growing threat existed toward their way of life. Ultimately, the slavery issue divided the North & South.
Douglas created the idea of popular sovereignty and this principle was passed by the federal government in the 1850s, and allowed states to decide whether or not to be free or house slavery. As more states claimed to be free soil, the slavery extension issue in new territories and states worsened (Lincoln-Douglas Debates).
Abraham Lincoln Presidency
We want to be on our own! Let us break away! ~South
The southern states felt that the federal government was trying to take away their rights and powers, especially when the Compromise of 1850 was passed by Congress. This compromise restricted the expansion of slavery into any new territories acquired from Mexico by the United States, including California.
When the Kansas-Nebraska act was passed in 1854, the citizens were allowed to decide whether or not they wanted to become free soil or endorse slavery within their borders. The issue regarding the presence of slavery was unresolved and continued for years in a series of bloody local battles.
Abraham Lincoln's election as President of the United States was the straw that broke the camel's back. The South felt that his presidency favored the North because he hated slavery, believed in equal rights for all, and hated the South... all odds were against the South.
A clear rift between the North and South caused the southern states to decide they no longer wanted to be a part of the United States. In an effort to preserve the peace and unity of the nation and stop the southern states from seceding, the Civil War ensued in 1861.