What Congressional event first indicated to northerners and southerners that their respective regions were significantly and disturbingly different?

Lectures indicated that to qualify as a planter in the Old South, one had to own fifty or more slaves.  Lectures also noted that nearly all free southerners were planters.

In 1832, South Carolina nullified the federal tariff and refused to collect the tax.  President Andrew Jackson threatened to respond with force.   A civil war might have broken out at this point.  Why didn’t it, according to the lectures?

And how did the nation feel about  expansion? Who wrote that it was the “manifest design of Providence” that the United States expand as far as it could? When was this statement written? What is its significance?

Abraham Lincoln was assassinated during the second year of the Civil War.

The Civil War is typically broken down into two regions:  The War in the West and the War in the East.  Battles in the West include Vicksburg and New Orleans.   Battles of the East include Spotsylvania Court House, Cold Harbor, and Antietam.

The upper south hesitated to secede at first.  What action by Abraham Lincoln drove most of them out of the United States?

One question about the Alamo is why did Santa Anna attack this outpost?  It was way out on the frontier with fewer than 300 men inside.  Why bother attacking and killing the defenders?  Why not just go around it?

BEGIN THE CUMULATIVE SECTION.  Cumulative questions are worth five points.  Remember, if you see A and B or All of the above as options, always pick one of those options.   If you were a southerner, a historian, and looking to the coming Civil War in 1861 (and of course had access to class lectures), which of the following factors in Northern history might raise concern that the South would be taking on a pretty ferocious enemy?  Why?

Discuss the Dred Scott ruling.