- Balance of power: Admission of more free states led to a fear in the South that the power dynamics in the Senate and House of Representatives will shift the balance towards anti-slavery.
- Extension of slavery: Southern states advocated the right to hold slaves in the acquired territories that became states, further escalating disputes
- Rise of the abolitionist movement: The territorial gains from the Mexican war increased opposition to slavery by highlighting the contradiction between democracy spread abroad but not applied equally at home ( in reference to abolitionism).