What was the cotton gin? What effect did it have on American economy and culture?
It was a gadget that separated cotton from its seed, and it kicked of the industrial revolution in America.
Much of America's wealth in the late 18th/early 19th Centuries was tied to cotton. International demand for Southern cotton was practically limitless. and the only thing disrupting its supply was the time-consuming process of separating it from its seed. Previously, the seed was separated out by hand by a worker with a knife, and it was a slow and dangerous process.
Eli Whitney allegedly watched a cat swipe at a chicken through a wire fence and got the idea for the cotton gin, introduced in 1791. It put the seed on one side of a rotating sawtooth blade and the cotton on the other, and it separated them quickly. Cotton became more profitable to raise and sell. Newly-wealthy Southern landowners sank all their money into more land and more slaves.
Abolitionist sentiment grew in the North, while the wealthiest Southerners doubled down on slave ownership. Similar technological innovations kicked off the Industrial Revolution in America and also made owners of other industries (tobacco, firearms, corn, liquor) insanely wealthy as well. They also set opposing forces towards an inevitable Civil War.