Cotton gin

A cotton gin—meaning "cotton engine"—is a machine that quickly and easily separates cotton fibers from their seeds, enabling much greater productivity than manual cotton separation. The separated seeds may be used to grow more cotton or to produce cottonseed oil. Handheld roller gins had been used in the Indian subcontinent since at earliest 500 and later in other regions. The Indian worm-gear roller gin was invented sometime around the 16th century and has, according to Lakwete, remained virtually unchanged up to the present time.

A modern mechanical cotton gin was created by American inventor Eli Whitney in 1793 and patented in 1794. Whitney's gin used a combination of a wire screen and small wire hooks to pull the cotton through, while brushes continuously removed the loose cotton lint to prevent jams. It made cotton farming more profitable, leading to a boom in cotton production in the United States. This inadvertently led to an increase in the use of slaves. Whitney had hoped his invention would do the opposite by reducing the amount of labor needed to process cotton, but he never invented a machine to harvest cotton. That job still had to be done by hand. Cotton harvesting machines did not show up until the 1930s. So as cotton farmers expanded their plantations, they bought more slaves to pick the cotton.

Modern automated cotton gins use multiple powered cleaning cylinders and saws, and offer far higher productivity than their hand-powered precursors.