Sectionalism between North and South, 1844-1860 I. The Mexican CessionA. An intense debate raged over whether slavery should be allowed in the Mexican Cession. 1. Wilmot Proviso, 1848: Proposed law passed by the House (but defeated in the Senate) to forbid slavery in the Mexican Cession a. It was supported by northern free-soilers and abolitionists. b. It was blocked in Congress by southern senators. •Southerners were infuriated that southern soldiers had helped win the Mexican-American War but that northerners would try to exclude slavery from hard-won territory. 2. Significance: The Wilmot Proviso brought slavery into the forefront of American politics until the Civil War. 3. The issue threatened to split both Whigs and Democrats along sectional lines. B. "Popular Sovereignty" emerged as a way to avoid the issue of slavery in the Mexican Cession and other western territories. 1. Definition: The sovereign people of a territory should decide for themselves the status of slavery. 2. Lewis Cass, the Democratic candidate for president in 1848, introduced the idea of popular sovereignty. •Polk was in poor health and decided not to run for reelection. 3. The idea was supported by many because it appealed to the democratic tradition of local rights. •Politicians saw it as a viable compromise between extending slavery (southern view) and banning it (northern Whig view). 4. Popular Sovereignty proved inadequate in averting a civil war. C. Election of 1848 1. The Whigs nominated Zachary Taylor, the "Hero of Buena Vista" •He appeared highly electable as he was neutral on the slave issue, yet he owned slaves on his Louisiana sugar plantation. 2. The Democrats nominated Lewis Cass 3. The new Free-Soil partynominated former president Martin Van Buren. 4. Electoral College Result: Taylor 163, Cass 127, Van Buren 0 •The Free-Soilers won no states and did not impact the outcome of the election.