1. Expansion of the Cotton Kingdom: The deep south was predominantly reliant on cotton production, and the institution of slavery was crucial for the plantations to sustain their high production levels. Cotton was lucrative cash crop, and the demand for it was increasing globally, leading to a constant demand for more Land and labor.
2. Acquisition of New Territories: The annexation of Texas and subsequent westward expansions, including the Mexican Cession, were strongly influenced by the desire to acquire new territories suitable for the expansion of slavery. The addition of these territories widened the reach of the plantation systems.
3. Political conflicts: The issue of slavery deeply divided the nation and ignited political conflicts between pro-slavery and anti-slavery factions. The westward expansion further intensified these conflicts as the admission of new states to the Union depended on whether they would permit slavery or be a 'free state.' The Missouri Compromise 1820, Kansas-Nebraska Act of 1854, and other legislation attempted to address these tensions but ultimately failed to resolve them and ultimately contributed to the outbreak of the Civil war.
4. Free Soil Movement: The westward expansion also fueled the opposition to slavery. Groups like the Free Soil Party argued that new territories in the west should be reserved for free white settlers and that slavery should be restricted to existing slave states. This movement further polarized the North and the South and contributed to the growing anti-slavery sentiments in the nation.
5. Dred Scott Decision: The Supreme Court's Dred Scott decision in 1857 further escalated the tensions regarding slavery in the west and contributed to the nation's division. This ruling effectively denied citizenship to African Americans and upheld the legality of slavery in territories acquired through westward expansion.
In summary, westward expansions in the 19th century were deeply intertwined with the institution of slavery. Economic, political, and ideological factors related to slavery had a profound impact on the acquisition and development of new territories and shaped the course of American history.