American inventor Eli Whitney (1765–1825) is credited with developing the cotton gin, a machine that removes cottonseeds from cotton fibers. A simple cotton gin (called the churka) dates back to ancient India (300 B.C.). But Whitney’s gin would prove to be far superior. In 1792 Whitney, who had recently graduated from Yale University, was visiting the Georgia plantation owned by Catharine Littlefield Greene, widow of American Revolution (1775–83) hero General Nathanael Greene (1742–1786). Whitney observed that short-staple (or upland) cotton, which has green seeds that are difficult to separate from the fiber, differs from long-staple (also called Sea Island) cotton, which has black seeds that are easily separated. The latter was the staple of American commerce at the time. In 1793 Whitney, who is described as a mechanical genius, completed an invention that could be used to clean bolls of short-staple cotton of their seeds; he patented it the next year.

The machine worked by turning a crank, which caused a cylinder covered with wire teeth to revolve; the teeth pulled the cotton fiber, carrying it through slots in the cylinder as it revolved; since the slots were too small for the seeds, they were left behind; a roller with brushes then removed the fibers from the wire teeth. The cotton gin revolutionized the American textiles industry, which was then but a fledgling concern. The increase in cotton production was as much as fiftyfold: One large gin could process 50 times the cotton that a (slave) laborer could in a day. Soon plantations and farms were supplying huge amounts of cotton to textile mills in the Northeast, where in 1790 another inventor, British-born industrialist Samuel Slater (1768–1835), had built the first successful water-powered machines for spinning cotton. Together the inventions founded the American cotton industry. Whitney struggled to protect his patent, but imitations of his invention were already in production, prompting the U.S. government to allow his patent to expire. Though he did not profit from his cotton gin, he went on to devise a system of interchangeable parts, which introduced the idea of mass production and revolutionized manufacturing.