That was not the issue as much as demographics were. The slave population grew far faster than the white population. By 1860, several of the deep South states had larger slave than free populations. That was fine -- to a point, as long as the demand for slaves in newly settled areas continued. The delemia of the slave economy was two fold. First, minus expansion, with a rapidly increasing supply of slaves and a deminishing demand as the plantation system reached its geographical limits, the value of slaves would plumet destroying the largest single source of wealth in the deep south especially.
Secondly, slavery contained within its current limits would have over another generation or so placed the ever smaller white population in very great risk from a hostile black population. Expansion was also a safety valve that kept the slave populations within controllable limits.
Lincoln and the Republican party's opposition to the further expansion of slavery is what drove the south into secession. They saw their lives and fortunes at risk if slavery were to be contained.
Tough to grow cotton in Nebraska.
True, but the gold, silver and copper mines of the west would have been worked by slaves instead of free men if the Slaveocracy had their way with expansion.
I’m afraid I can’t entirely buy your reasoning there. Regardless of how much territory was devoted to slavery, the differential population expansion would be the same. The proportion between black and white populations would be the same whether slavery was limited to the South or was able to expand into Mexico, the Caribbean and the rest of Latin America.
IOW, whites would still face the chance of being outnumbered, with the primary difference whether this would be in a large territory or a relatively small one.
The only way to change this would be to reduce black birth rates, not likely since every birth meant money in their pockets, or great expand white immigration. This also wasn’t likely, as darn few Europeans wanted to move to a slave country.
The value of slaves was related primarily to the price of cotton. If cotton dropped, demand for slaves to pick it would plummet. As long as cotton prices remained high, so would slave prices. Of course, as any idiot knows or should, high prices encourage others to enter the field and cause over-production and a price crash. Southerners were riding a cotton price bubble that would eventually collapse, taking their prosperity with it. That’s what you get with a one-crop economy.