Why did Lincoln's election prompt the Southern states to secede?

Question: Why did Lincoln's election prompt the Southern states to secede? I am confused by that timing: Lincoln seemed to have a very moderate anti-slavery position. He was staunchly opposed to the expansion of slavery to new states, but even years later did not believe that slavery could be interfered with in states where it was established (except as a war power; or unless there was a constitutional amendment).

Successions began(Nov 10 1860) when South Carolina became the first state to leave the union before Lincoln even took office(Mar 4, 1861). I think Lincoln's election(Nov 6, 1860) was part of the provocation, perhaps the lesser part. The Republican party was founded to end slavery and the election of a President even a moderate one empowered the radicals who made up the majority of his party. It was an affront to southern political leaders who had fought a generational battle over slavery with northern politicians. This generational struggle had radicalized both factions.

Besides that, and perhaps the greater provocation was the result of Kansas Nebraska's statehood. The Kansas Nebraska Act was at first heralded as a victory for the South. It proclaimed for the first time popular sovereignty would decide if states entered the union as slave or free. Prior to this act statehood was bestowed in pairs to keep the slave/ free state equilibrium in the senate in tact. This ensured the slave states could protect slavery from federal action. After this act it eventually became apparent when given a choice new states would all choose to be free and not slave. This is because the settlers for these states overwhelmingly came from the more populous north, or from Europe where slavery was already illegal. Also the blue collar manual laborers who overwhelmingly went west, saw slaves as competition for jobs.

The south fought a losing 7 year war in bleeding Kansas in an attempt to coerce an pro slavery popular mandate but ultimately failed. In April of 1860 the US House of Representatives had voted on a state constitution previously ratified by the Kansas state legislature. One of the final acts for Kansas to achieve statehood. This constitution would make Kansas a free state. The South blocked Kansas's admission with their votes in the Senate, but that was always going to be a short term solution. When it became apparent the South would not be able to continue to block Kansas, the die was cast.

This is what symbolized for Lincoln and the South the beginning of the end of Slavery. The vast western territory was going to yield another 7 states and all of them were likely to be free states. The South's power and influence to protect slavery was broken and it was only going to get weaker. Slavery would end, whether Lincoln ended it in 1861 or not and everybody knew it. That is ultimately why the South seceded. It is also why you view Lincoln as a moderate. The North had won, Lincoln's only moderation was his unwillingness to fight a war, the most costly war in american lives in order to end it a decade or two earlier. It is why for Lincoln, the civil war was about preserving the union and not ending slavery. Because thanks to Kansas Nebraska preserving the Union was synonymous with ending slavery. For the south this meant either leave the union or give up slavery. Else slavery would die a death of a thousand cuts as it would be undefended on Capital hill. Likely even more bitter than that for southern leadership was to lose the bitter generational war they had waged with the north in the political arena.

Timeline:

• April, 1860 the U.S. House votes to admit Kansas under the Wyandotte Constitution (free state)
• November 6, 1860 Lincoln is elected
• November 10, 1860 South Carolina leads 11 states into succession freeing the senate deadlock to admit Kansas.
• January 29, 1861 Kansas enters the Union as a free state
• March 4, 1861 Lincoln's inauguration (when he takes office).
• April 12, 1861 - battle of fort Sumpter the first shots of the American civil war are fired.

It's important to understand just how little support Lincoln had in the south. This map shows the proportion of the population voting for Lincoln. The results on this map are hard to fathom with a modern understanding of politics. It wasn't that a huge majority of Southerners didn't want Lincoln, it was almost unanimous. In a two party system where candidates usually move towards the middle and have somewhat similar opinions and broad appeal, it was shocking to see a leader with no support in the South. Obviously the results would be very different if a huge portion of the southern population were not held in bondage and denied suffrage, but slaves were not consulted about the decision to secede. Southern voters were, and they saw Lincoln's election as a very clear symbol of how different the interests of the union government were from the interests of southern voters.

In 1860, with 40% of the vote, Abraham Lincoln won a victory in the electoral college by sweeping nearly all of the Northern states, as well as the two Western states (California and Oregon). Not a single "Southern" state voted for Lincoln, and yet suddenly this abolitionist was declared President. Yes, the South wanted to save the institution of slavery, but they were also tired of the relatively wealthy and semi-industrialized North dictating politics, culture and morality to the poorer and largely agricultural South. Talks of secession had been brewing for years; Lincoln's purely Northern election was merely the straw.

Lincoln, like the majority of the North, likely believed that abolishing slavery would lead to civil war, and so did not consider it a practical option. Of course, once the South seceded and initiated the Civil War, that impediment to abolishing slavery vanished.

So your question is well founded - it seems that secession and initiating civil war was counter to the South's aim of preserving slavery, so why did it happen?

The answer to that lies in balance of Free and Slave states. Even before Lincoln's election, the balance in senate had shifted in favor of free states. While Lincoln's election posed no immediate threat to slavery, it certainly emphasized the fact that slavery was already an anachronism headed for extinction.

It is often seen human nature to blame others for your own problems. The South blamed the North for the fact that slavery was doomed. Just consider, if the South had won the civil war, would there still be slavery in the South? Definitely not.

Nо, the timing of secession and Lincoln's election are not coincidence, and Southern states were not reacting to Lincoln as person; they were reacting to political platform of winning party.

Southerners were threatening succession in 1856, if Republican Fremont elected president.

Obviously threats of secession from southern states if Fremont were elected had frightened a considerable number of conservative northern voters

^{The 1856 Presidential Election}

During 1850 crisis (ended with compromise), Mississippi state convention declared what actions (toward the slavery) would trigger state resistance and possible secession; among them:

5. The passage of any law by Congress prohibiting slavery in any of the territories

^{Journal of the convention of the state of Mississippi, and the act calling the same, Pg 20}

After 1860 election, it was very possible that such law would be passed, and not vetoed by president. Instead of fighting this in Congress, Southerners (at the urge of fire-eaters) decided on immediate extralegal secession and formed new country with slavery constitutional perpetuation.

UPDATE: Forgot to mention, that prohibiting slavery on federal territories was major plank of Republican platform, in both 1856 and 1860

tl;dr

Slavery and state's rights were an existential issue for the South; they could no longer contemplate "compromise" or "moderation".

From before the foundation of the Republic, there was an existential tension between the Southern vision of the future and the Northern vision of the future. The only thing keeping them together was the desire to be independent and the leadership of politicians. Their positions on slavery and states rights diverged even more sharply in the pre-war period.

From the South's point of view, there was no such thing as a moderate anti-slavery position. They believed that slavery was culturally and economically vital to their existence; they believed that the North would continue to undermine and eliminate their peculiar and essential institution. More importantly than that, if the North demanded to control the South to the extent of destroying this institution, then there was no limit to what the North would do. From the South's point of view, "moderate anti-slavery" was like "a moderate bit of cyanide" - on existential issues, one cannot be moderate.