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 Katherine Greene, widow of American Revolution hero General Nathaniel 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 removed. 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 textile industry which was then but a fledgling concern. The increase in the production of processed cotton was phenomenal. One large gin could process fifty 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 England and in the Northeast of the United States where in 1790 another inventor, British-born industrialist Samuel Slater, had built the first successful American water-powered machines for spinning cotton cloth. Together the inventions founded the American cotton industry. Whitney struggled to protect his patent. His problem was getting Southern courts to enforce his patent. The courts, dominated by plantation interests, refused in every case to uphold his patent.
For the southern slaves, Whitney's invention was a disaster. Prior to the invention of the cotton gin a consensus had prevailed that slavery would fade away. There were the moral objections to slavery (which, however, for the first 250 years of its existence in colonial and early republican America, never seemed to be quite persuasive enough to put an end to it). But there was also the fact that slavery was inefficient when applied to most kinds of agriculture or skilled production. Cotton, however, was a labor-intensive crop requiring large gangs of workers moving through the fields at different times in the growing cycle, planting, hoeing, and harvesting. With the invention of the "gin," cotton suddenly became a highly profitable cash crop. Although the Constitution had stipulated that the importation of slaves would end in 1808, now the price of slaves rose and the slave system was reinvigorated at the very time when it was being outlawed in most of the rest of the world.