Whitney applied for a patent on October 28, 1793 and on March 14th of the following year was granted a U.S. patent for his machine, which removed seeds from the cotton fiber.
There’s a reason American schools stress the importance of Whitney’s invention, and you can learn more about it here in this teaching plan.
Whitney got the patent and the credit, but he didn’t get rich off the invention that altered the American economy. Some people say he didn’t even invent the thing — that he was merely a hired hand who built it under the direction of the widow he worked for, Catherine Greene. Women in those days were not allowed to apply for patents, so there’s no documentation to back up the claim that Greene invented it (another version has it that Whitney came up with the idea, but that Greene added a crucial element that made it work).
It’s clear that Whitney worked for Greene, and that Greene, a plantation owner, knew more about the problems in harvesting cotton. It’s also clear that Whitney was a mechanical whiz kid.
In any case, the device worked so well it was copied by others in a hurry, which led to a prolonged legal battle that eventually forced Greene to sell her plantation and Whitney to move on to other things.