Final answer:
The cotton gin, invented in 1793 by Eli Whitney, significantly increased the demand for slave labor in the American South by boosting cotton production, leading to the expanded use of slavery and an increase in the value of enslaved individuals.
Step-by-step explanation:
The invention that significantly increased the value and demand for slaves in the South was the cotton gin. Invented by Eli Whitney in 1793, this device revolutionized the production of cotton by vastly improving the efficiency with which cotton could be cleaned, separating the cotton fibers from seeds. As the cotton industry expanded, the demand for slave labor to plant, harvest, and process the cotton also grew.
Cotton became the principal crop of the South and contributed to its economic growth, which was supported by the institution of slavery. By the 1850s, the Southern economy was highly dependent on the production of cotton, and enslaved people were considered valuable assets for maintaining and increasing cotton production. As a result, the price of enslaved individuals essentially doubled by the 1850s compared to the 1820s.
The dependence on cotton and enslavement led to various economic and social dynamics in the South, including a robust domestic slave trade. The domestic slave trade was driven by the demand for labor in the booming cotton fields, leading to increased value and demand for enslaved individuals across the Southern states.