Final answer:
Approximately three-quarters of all slaves were dedicated to cultivating cotton by the eve of the Civil War, as cotton had become the Southern economy's primary cash crop and the South produced the bulk of the world's supply.
Step-by-step explanation:
On the eve of the Civil War, approximately three-quarters of all slaves were engaged in cotton cultivation. This overwhelming involvement in cotton production is due to its emergence as the primary cash crop and driving force behind the Southern economy. The development of the cotton gin by Eli Whitney in 1793 significantly eased the process of separating seeds from cotton, contributing to cotton's predominance. By 1860, the South produced two-thirds of the world's cotton supply, and the number of enslaved individuals growing cotton had risen to 1.8 million out of 3.2 million in the slave states. Cotton's profitability directly relied on the institution of slavery, marking it a grim cornerstone of Southern prosperity and economic activity.