How effective was the cotton gin at processing cotton?

Farmers were able to plant more cotton.  Cotton is easy to grow but because it was so difficult to clean, cotton was not a cash crop.  Tobacco and indigo were the South’s cash crops.  Tobacco is difficult to grow.  Tobacco wears out the land and the land must be given a rest once every 7 years.  But cotton can grow anywhere, even on land that is drained of its nutrients.

Now that cotton is easier to clean and since it grows easily, cotton became the number one cash crop in the South.  The farmers needed more land to grow cotton.  They took the land from the Native Americans.  The farmers needed more workers.  Slaves were the free labor that the farmers needed to harvest the cotton.

This growth of cotton production affected the world.  The Northern part of the United States bought more cotton and built more textile mills.  England built more textile mills and demanded much more cotton.  These were two big markets to which the South sold their cotton.  The South was not able to build textile mills because their capital was tied up in their slaves so that they could produce more cotton.  The South also did not have the need or the capital to build up a good transportation system, such as canals and railroads. 
During the Civil War, the South had many disadvantages over the North.  A large portion of their population were uneducated slaves.  They had no factories to produce goods and to become self sufficient when they separated from the North.  Because the South had not built up a good transportation system, they were not able to move men and supplies easily across the country, as the North was able to do.

By 1860, cotton was a cash crop.  Cotton production in the South had increased.  The number of slaves in the United States had increased.  The dependency on slaves had increased.  Capital had been invested in slaves, not in transportation or factories.  All this happened because of a very simple machine, the cotton gin.
 
hope this helps.