Why did the South secede?

Answer 1

Slavery. They felt it was about to be abolished and wanted to keep it.

You will hear lots of revisionist history saying it was because of "tariffs" or "states' rights". All of that is nonsense. Almost immediately after the Civil War ended, Southern sympathizers started a misinformation campaign, talking about a "Lost Cause" and how the noble Southerners only wanted to protect states rights from an oppressive Federal government. It's the rare case of history being "written by the loser".

However, if you look at the secession bills each seceding state passed, they actually opposed states' rights- "states rights" refers to the idea that it's preferable for states to make their own laws than for the federal government to do it. The Southern lawmakers, in their secession bills, cited laws passed in other, primarily Northern, states that they didn't like. For example, they were upset that Maine passed a law making it legal for blacks to vote there. They were upset that New York passed a law saying it was illegal to bring slaves there from another state. In each bill, they explicitly state they are quitting because they want to keep slavery- Mississippi even cited a form of white supremacy, saying that it's unnatural for blacks to be equal to whites!

And then the short-lived Constitution of the Confederate States made a point of saying that slavery would always be legal, even if new states were later added-the USA had, in preceding years, traditionally tried to keep the number of slave and free states about equal- see, for example, the Missouri Compromise.

Rather than just learning to live with the Northern laws, and with Abraham Lincoln becoming president in spring of 1861 (he was known for being an abolitionist- although he had famously stated he would rather allow slavery to continue than let the Union break apart), they chose to try to quit altogether, starting with South Carolina, which had already made threats to do so in the past (as in the Nullification Crisis of the late 1820's).

And, to settle the whole thing, there was a very nasty war, and then in 1869, the US Supreme Court ruled in Texas v. Whitethat secession is illegal.

Answer 2

The south seceded because they wanted states to be able to decide on their own issues. They didn't want the government to tell them what to do.