Eli Whitney's Inventions Changed America and Unfortunately Caused a Rise in the Use of Slavery

Eli Whitney's inventions created thousands of jobs for the American public pre-civil war, but they also inadvertently caused a sharp increase in the popularity of slavery.
Trevor English

American Inventor Eli Whitney was one of the most prominent inventors of his time. He utilized machines and machinery to create more jobs for the American working class in the late 1700s. 

His inventions played a large role in the pre-civil war American south's productivity and he was able to drastically improve the whole country's manufacturing output. In order to understand his impact on society better, let's take a look at the key things he invented during his time.

Cotton gin

When most people hear the name Eli Whitney, they think of the cotton gin. This machine was patented in 1794 and is basically a mechanical cotton sorting machine. The gin itself is actually short for engine. 

The device was made up of two wheels on an axle that were attached to a powered crank. The wheels had metal hooks all over them to grab onto the cotton as they rotated. These wheels overall were very sharp, almost like saw blades. When the cotton gin was loaded with cotton and activated, the wheels turned, the hooks caught the cotton, and slowly bits of cotton would be pulled through a screen. This process sorted the seeds and the hulls out from the cotton fibers. 

Whitney also built in a wire brush that swept the cotton off of the blades every so often to keep the machine from jamming and having to be manually fixed.

This entire machine mechanized a process that was very laborious and quite tedious. Separating cotton from the seeds and hulls up to this time would've been mostly done by slaves or low paid workers. It would've resulted in bloody hands and the output of cotton would've been minimal per person. 

Cotton cultivated in the south was particularly hard to sort due to the conditions it was grown under. Known as "green seed" cotton, it would require 10 hours of hand labor to produce a single unit of useable cotton fibers. Whitney's cotton gin could do the day's work of two to three men in roughly an hour.


Due to the fact that it was previously slaves doing the gin's work, you might think that Whitney's invention actually lessened the need for slave labor in the U.S., but that, unfortunately, wasn't the case. 

The cotton gin meant that even small farms could cultivate cotton with a small labor force. In essence, the gin allowed for cotton production to spread across the entirety of the south, from farms small to large. After it's invention, raw cotton yield doubled every decade until America was supplying 3/4s of the entire world's cotton in the 1850s. All of this success was based on the back of Whitney's cotton gin, though much more soberingly, it was based on the back of thousands to millions of slaves, an indirect result of mechanization in the Southern U.S. at the time.

Most Popular

Mass production

Eli Whitney was a great mechanical thinker. While the cotton gin was his most famous and perhaps most impactful invention, he went on to create many other notable things. In premonition of the U.S.'s possible war with France, Whitney won a contract to produce 10 to 15,000 muskets in two years for the U.S. War Department. Notably, he won this contract with no prior experience in firearms manufacturing. 

Eli Whitney's Inventions Changed America and Unfortunately Caused a Rise in the Use of Slavery
Source: Sächsische Maschinenfabrik/Wikimedia

That meant that Whitney was going to need to get creative in order to meet his deadline. It was this initial project and the methods he developed from it that lead him to be the father of the American mass-production system. In this process, he claimed to have produced a rifle that worked with interchangeable parts, making fixing guns in the field a snap.

However, while he did present this invention in a demonstration before the government, we now know it was faked to buy him more time in the production process. U.S. textbooks still largely claim Eli Whitney was the creator of interchangeable parts, which he called his uniformity system. Given that we now know he didn't actually achieve that invention, he wasn't even the first to suggest the idea, which means that his credit for that invention isn't really based on anything. 

That said, Whitney still demonstrated that mass production was a plausible means of production.

The milling process

Whitney's last key invention during his lifetime was that of the milling process, largely tied to his mass production process. 

Milling machines existed before Whitney invented his own, but his machine in particular was so successful and well built that it remained a standard in the industry for 150 years. It went on to create thousands of products, even after Whitney's death. 

It's for this reason, like we see with many other inventions, that Whitney is credited as the key inventor of the milling machine. 

Eli Whitney's Inventions Changed America and Unfortunately Caused a Rise in the Use of Slavery
Source: Public Domain/Wikimedia

His machine specifically required the clamping of metal to a workbench and attaching a pattern to its top. Then, a worker would manually roll a sharp-toothed wheel along the top pattern to cut out that part. The previous method would've involved chiseling or cutting the material by hand.

This machine played a significant role in the production of muskets for the American military.

These three inventions may not seem like all that much, but the results of Whitney's work in industry created thousands – if not millions – of jobs for the American people. Eli Whitney ended up passing away 35 years before the Civil War, meaning that he never saw the culmination of the effects that his cotton gin had on the American people. Whitney was a great mind and his work serves as a great example of how good engineering can have unintended consequences on lives across the world.