Final Answer:
The economic category was most responsible for the expansion of slavery in the United States.
Step-by-step explanation:
The expansion of slavery in the United States can be primarily attributed to economic factors. The Southern agrarian economy, heavily reliant on cash crops like tobacco, rice, and later cotton, demanded a large and inexpensive labor force. Slavery provided a ready workforce that could be exploited for agricultural production. The profitability of plantation-based agriculture in the South became deeply intertwined with the institution of slavery, as the economic benefits of using enslaved labor contributed significantly to the expansion of slavery.
The economic category encompasses the financial interests of plantation owners and the broader Southern economy, which profited from the labor-intensive cultivation of cash crops. The institution of slavery provided a cheap source of labor that fueled the economic prosperity of the Southern states. As demand for cash crops increased, so did the demand for enslaved labor. The economic incentives created a self-reinforcing cycle, leading to the expansion of slavery as an integral component of the Southern economic system.
While other categories, such as social and political factors, also played roles in the perpetuation of slavery, it was the economic imperative that underpinned the expansion of slavery in the United States. The economic benefits derived from the institution of slavery created powerful motivations for its continuation and growth, shaping the trajectory of American history and contributing to the tensions that eventually led to the Civil War.