Which crop became the cornerstone of the Southern economy in the early 19th century?

Cotton became the cornerstone of the Southern economy in the early 19th century due to its significant role in both agriculture and the emerging textile industry. The invention of the cotton gin by Eli Whitney in 1793 revolutionized the processing of cotton, making it easier to separate the fibers from the seeds. This innovation spurred a dramatic increase in cotton production, leading Southern states to focus heavily on this cash crop.

The rise of cotton not only contributed to the economic prosperity of the South, but it also became integral to the nation's overall economy, as cotton was in high demand both domestically and internationally, particularly in Britain where textile manufacturing was booming. The Southern economy became heavily dependent on this single crop, which also reinforced the institution of slavery, as plantation owners relied on enslaved labor to cultivate and harvest cotton on a large scale.

Other crops like tobacco, rice, and indigo were important to the Southern economy prior to the cotton boom, but none had the same transformative effect as cotton did during the early 19th century. Cotton established itself as the dominant agricultural product, fundamentally shaping the economic landscape of the South and influencing its social structure, politics, and culture.