Here are some of the reasons why cotton was so important to the United States:
* Cotton was a major export commodity. The United States was the largest producer of cotton in the world, and it exported the majority of its crop to Europe. Cotton was used to make a variety of products, including clothing, bedding, and furniture.
* Cotton was a source of wealth for many people in the South. The cultivation and sale of cotton made many landowners in the South very wealthy. This wealth was used to support a lavish lifestyle, and it also helped to pay for the construction of infrastructure and other improvements in the region.
* Cotton was a political issue. The debate over slavery was closely tied to the issue of cotton. Many Northerners opposed the expansion of slavery into new territories because they feared that it would give the South too much power. This conflict eventually led to the Civil War.
The phrase "cotton is king" was used to emphasize the importance of cotton to the United States. It was a reminder that the country's economy was heavily dependent on this crop, and that the South was the center of cotton production.