Until the 1790s growers were limited to producing the quantity of cotton that could be processed by slaves. Separating the seeds from cotton was time consuming and labor intensive. The bolls (cottonseed pods) were dried in front of a fire, and the seeds were picked out by hand. In 1793 American inventor Eli Whitney (1765–1825) introduced the cotton gin. A revolutionary laborsaving machine, it could clean 50 times more cotton fiber in one day than a human. Though Whitney patented the machine in 1794, imitations were quickly put into production by shrewd businessmen who realized the impact the gin could have on the nation's cotton industry. Just before Whitney developed the gin another inventor, British-born Samuel Slater (1768–1835), introduced the first successful water-powered machines for spinning cotton at a Rhode Island mill in 1790.
There was no shortage of demand for the fiber. As the 1800s dawned, machinery had made cotton the center of the nation's emerging textile industry. Soon New England was dotted with textile factories. Growers in the South increased cotton production to keep up with factories' demands. Slave labor and excellent growing conditions in the southern states (especially Alabama, Mississippi, Georgia, and South Carolina) combined to dramatically increase production. By 1849 annual cotton exports had reached $66 million and accounted for roughly two-fifths of total U.S. exports.
Cotton came at a dear price: laborers in the North's textile factories worked under difficult and sometimes dangerous circumstances, in the South cotton crops were planted and harvested by slaves. As abolitionists became increasingly vocal and demanded that the U.S. government legislate the end of slavery, southern growers defended the system, saying that their livelihoods and the South's economy depended on it.
King cotton became an expression coined during the mid-1800s when the economies of southern states were heavily dependent on the cotton industry. In 1858 South Carolina Senator James Henry Hammond (1807–64) taunted northern sympathizers, saying "You dare not make war on cotton—no power on earth dares make war upon it. Cotton is king." Hammond was not the first to use the phrase; it was coined three years earlier in the title of a book. The South's dependence on cotton contributed to the deepening North-South divide in the nation. By the time the Civil War (1861–65) began, the southern United States supplied twothirds of the world's cotton.
See also: Abolition, Cotton Gin, Samuel Slater, Slavery, Spinning Mills