What led the stated to secede from the union in 1860 and 1861?

Answer 1

Most of these answers have some partial truths to them, but let me wrap it all up for you.
It was actually the election of Abraham Lincoln as President that proved to be the final trigger that startes the secession of 11 southern states. In fact, by the time Lincoln actually took over office (three months after being elected) South Carolina had already seceded.
The south, or the Confederacy, as it was now called, was afraid that Lincoln would abolish slavery, thus depriving them of their #1 commodity. Since cotton was the cash crop, they needed slaves to pick it and process it. Especially since the invention of the cotton gin several years before, which allowed for a drastic increase in cotton processing.
The South had, for a long time been resentful of paying taxes, which they considered were being used primarily for Northern infrastructure, like railroads and factories and such. But the tax issue probably could have been resolved without secesssion. It was the election of Lincoln that proved to be the last straw. The Confederacy always felt that their cause was much like that of the colonists' cause when they revolted from England back in 1776.
Thus, the main issue of the civil war was States Rights. But slavery was the main bone of contention pertaining to these rights.

Answer 2

The southern states seceded from the union due to many problems that resulted from slavery. They wanted to keep their slaves, but northern congressmen wanted to abolish it. So, the southern states seceded.
The Civil War was started over secession, not slavery.
The taxation problem was the Tariff of Abominations that the south hated, about 40 years prior secession. South Carolina threatened secession over that, but Jackson threatened to force S. C. to abide by the federal laws.

Answer 3

Same as in 1776, big government riding rough shod over the rights of the states. Unfair taxation.

Answer 4

Actually, it was about Taxation without Representation (specifically in the Carolinas), NOT slavery.

Answer 5

Lack of a good pizza joint in the area.