In 1794, Eli Whitney patented a new kind of cotton gin. His invention, using rotating brushes and teeth to remove the seeds from cotton, was quickly pirated by others.
Southern plantation owners depended on slaves for labor-intensive crops such as rice, sugar, tobacco, and especially cotton. As the market demand for cotton increased in the early 1800s, the Southern cotton industry expanded dramatically, as did the system of slave labor it relied on.
Kendrick, Kathleen M. and Peter C. Liebhold. Smithsonian Treasures of American History
National Museum of American History. Treasures of American History online exhibition