
When Eli Whitney left New England and headed South in 1792, he had no idea that he would invent a machine that would change the history of America. After the invention of cotton gin the production of raw cotton doubled every decade and the demand was increasing by the other inventions of the industrial revolution such as the machines to spin and weave it and the steamboat to transport it. By mid-century America was growing three-quarters of the world’s supply of cotton. But however this great invention played a big role in increasing slavery. Cotton gin only reduced the labor of removing seeds so the production was increasing and slaves had to grow and pick more than double cotton. In 1790 there were six slave states; in 1860 there were 15. In 1808 southerners imported about 80,000 Africans.
http://www.history.com/topics/inventions/cotton-gin-and-eli-whitney
Eli Whitney is always remembered as the inventor of the cotton gin, but often forgotten that he was also the inventor of the mass production method. In 1798 he figured out how to manufacture interchangeable parts. If his invention of cotton gin led to more cotton production and slavery, his technology also helped North won the Civil War. So Eli Whitney made very big impact on American history in good and bad ways.
Do you think every new invention brings both good and bad consequences?

