The Industrial Revolution created factories and looms in 1730s Britain that could quickly process cotton to make cloth and then clothing. The demand for cotton quickly grew. Some farmers worked to fulfill that need, but cotton was not easy to grow. The trouble lay in the need for cotton to be seeded. The many seeds in the cotton had to be hand removed, taking an average worker a day to seed a pound of cotton. For decades, cotton farmers barely scraped by in a necessary but unprofitable industry. But with the invention of the cotton gin, the process suddenly became 10 times faster, and the plant became the cash crop. By the turn of the century, cotton had ballooned from a $150,000 business to a $8 million dollar powerhouse. Plantation owners wanted to get in the business as much as possible, so they purchased more and more slaves, revitalizing the slave trade. It made South, and to some degree, the US as a whole, rich, but it would ultimately lead to the Civil War as America grappled with the constitutionality and morality of bondage.
Today, cotton is still a large industry in the US, valued at $25 billion annually. But of course, much of the demand for materials from the manufacturing industry has shifted to polymer fabrics.