Machine for cleaning cotton of its seeds. The design that became standard was invented in the U.S. by Eli Whitney in 1793. The mechanization of spinning in England had created a greatly expanded market for U.S. cotton, but production was bottlenecked by the manual removal of the seeds from the raw fibre. The cotton gin pulled the cotton through a set of wire teeth mounted on a revolving cylinder, the fibre passing through narrow slots in an iron breastwork too small to permit passage of the seed. The simplicity of the invention caused it to be widely copied. It is credited with making cotton the most important export crop of the U.S. before the American Civil War, as settlers and their slaves spread westward through prime cotton-growing regions of South Carolina, Georgia, Alabama, Mississippi, and Texas.