What invention is Eli Whitney best known for?

Eli Whitney is best known for inventing the cotton gin, a machine that revolutionized the cotton industry in the late 18th century. The cotton gin streamlined the process of separating cotton fibers from the seeds, which was previously a labor-intensive task that could only be done by hand. By significantly speeding up this process, Whitney's invention contributed to the growth of the cotton plantation system in the Southern United States, resulting in increased demand for slave labor and having a profound impact on the American economy and society.

The invention of the cotton gin is crucial to understanding the agricultural and economic developments of the time, as it played a pivotal role in making cotton a dominant cash crop. This development also had lasting effects on the Antebellum South, influencing social and economic structures that would persist until the Civil War.

In contrast, the other inventions listed—such as the steam engine, telegraph, and spinning jenny—are associated with different inventors and historical contexts. The steam engine, for instance, was primarily developed by James Watt and contributed to the Industrial Revolution, while the telegraph revolutionized communication, a field dominated by Samuel Morse. The spinning jenny, invented by James Hargreaves, was instrumental in the textile industry of Britain.