They attempted to prevent secession by protecting slavery where it already existed and extending the Missouri Compromise line.

They believed his anti-slavery stance threatened their way of life and the institution of slavery.

It raised the question of whether new territories acquired in the west would allow slavery.

It reignited tensions by raising the question of whether slavery would expand into the new territories.

It heightened Southern fears of a Northern conspiracy to incite slave revolts and further divided the nation.

It allowed popular sovereignty in Kansas and Nebraska, repealing the Missouri Compromise and leading to "Bleeding Kansas."

It was an attempt to incite a slave rebellion, increasing sectional tensions and fear in the South.

The issue of slavery in the territories, especially popular sovereignty.

It ended the Mexican-American War in 1848, ceding the Mexican Cession (including California and much of the Southwest) to the U.S. in exchange for $15 million.

It ruled that African Americans were not citizens and that Congress could not ban slavery in the territories.

It increased anti-slavery sentiment in the North and angered the South.

It proposed banning slavery in territories won from Mexico, intensifying North-South tensions over the expansion of slavery.

The annexation of Texas, disputes over the Texas-Mexico border, and U.S. desire for territorial expansion under Manifest Destiny.