Final answer:
Eli Whitney invented the cotton gin in 1793, which inadvertently increased the demand for slavery due to the need for mass production of short-staple cotton, leading to the westward expansion of slavery into new territories.
Step-by-step explanation:
The American inventor who revolutionized southern agriculture with his invention of the cotton gin in 1793 was Eli Whitney.
This invention significantly increased the efficiency of cotton production by quickly removing seeds from the raw cotton, which led to an unfortunate expansion of slavery as it made the cultivation of short staple cotton profitable and sparked a boom in the agriculture economy of the South.
Whitney's invention was meant to reduce the need for slave labor, but instead, it increased the demand for slaves to plant and pick the cotton. Despite his hopes and legal efforts to protect his invention, Whitney found that southern planters often replicated his cotton gin with minor modifications and he was unable to enforce his patent rights in the southern courts.
Westward Expansion of Slavery
As a result of this increased need for cotton production, the demand for more fertile land grew, leading to the westward expansion of slavery into states such as Alabama and Mississippi.
This expansion contributed to the establishment of nine new slave states between 1789 and 1860, entrenching slavery further into American society and economy and laying the foundation for future division and conflict.