In the 19th century Cotton developed and thrived in America's South, by mid 19th century the southern plantations industry was coined "King Cotton". The American crop was stronger than the India crop (The leader in cotton in the previous and early part of the 19th century).
It was the invention of the 18th century item by Eli Whitney that changed the industry. In the ten years after Eli invented the Cotton Gin, the industry went from thousands per year to 8 million. That made cotton the cash crop and the south grew rapidly with the demand for more and more cotton.
This also meant that slavery increased as well.
Here's one figure on the increase of production: In 1830 the south produced 720,000 bales in 1850 it produced 2.85 million by 1860 it was nearly 5 million. This meant that by the time of the Civil War Cotton was 60% of the export crop for the entire United States, bringing in an annual income of $300, 000, 000 per year.
This brought about the famous quote from Senator James Henry Hammond of South Carolina. "Without firing a gun, without drawing a sword, should they make war on us, we could bring the whole world to our feet... What would happen if no cotton was furnished for three years?... England would topple headlong and carry the whole civilized world with her save the South. No, you dare not to make war on cotton. No power on the earth dares to make war upon it. Cotton is King."