By 1800 or so, however, African American slavery was once again a thriving institution, especially in the Southern United States. One of the primary reasons for the re-invigoration of slavery was the invention and rapid widespread adoption of the cotton gin. This machine allowed Southern planters to grow a variety of cotton--short staple cotton--that was especially well suited to the climate of the Deep South. The bottle neck in growing this crop had always been the labor needed to remove the seeds from the cotton fibers. But Eli Whitney's gin made it much easier and more economical to do. This fact made cotton production much more profitable and hence very attractive to planters and farmers in the South. Still, growing cotton was very labor intensive and cotton growers needed a large supply of labor to tend the fields. African American slaves supplied this labor.