The invention of the cotton gin really impacted slavery in the early 1800s and beyond. The South had always had slaves. However, when the cotton gin was invented in 1794, the demand for slaves increased significantly.
In the South, two kinds of cotton were grown. Long staple cotton was grown along the coast. Machines could easily remove the seeds from the long staple cotton. However, since this kind of cotton could be grown only along the coast, there was a limited area where it could be grown. The other kind of cotton that was grown was short staple cotton. This type of cotton could be grown anywhere. However, the seeds had to be removed by hand. This was very difficult to do.
When the cotton gin was invented, it was now possible to remove seeds from short staple cotton by using this invention. This allowed much more cotton to be grown since short staple cotton could be grown anywhere. As a result, the demand for slaves increased significantly. The invention of the cotton gin helped to make cotton the main southern export by 1860. It also meant slavery would be very important in the South.