Eli Whitney's Cotton Gin's social and the industrial changes to the US it made.

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…the evolution of America into the mechanized world. The cotton gin overall, greatly affected people and industry worldwide. It led to the creation of many other useful inventions and not so useful inventions such as, umbrellas for your shoes. The point is, you have to invent and try something before you figure out if it will be useful or not and in Eli Whitney's case the cotton gin proved to be very, very useful indeed.