The cotton gin and the steam engine doomed the South, the first by making cotton an economically viable fabric, the second by powering English textile mills, cotton being suited to mechanized looms.
Inexpensive machine-made cotton fabric took the world of previously expensive homespun fabric by storm, and England had the Empire to sell it everywhere, creating their insatiable appetite for American cotton, coincidentally slave-grown. Thanks to British demand, beginning around 1820 in the South the fastest way to riches was your own cotton plantation. Cant grow cotton up North, so that was never an option up there.
Our politicians arise from among our wealthiest men, in the South their leaders were almost without exemption Planter Aristocracy, making decisions for and about cotton. By the time 1860 rolled around, fully 80% of the Southern economy concerned cotton, and one quarter of its population was enslaved, mostly for purposes of its cultivation.
At the start of the war the Confederacy actually tried to strongarm the British Empire into recognizing it as a legitimate government, by actually withholding exports of cotton to virtually its only customer, causing economic turmoil in Britain.
In response the British diversified their sources by introducing cotton cultivation to Egypt and India, depressing cotton prices and dooming the South to a period of post-bellum poverty.
