After the U.S. safeguarded vast new land assets in the Mexican War, the South and North brutally then disputed these lands and moved further apart, emphasizing sectional strife. When Northern congressmen maintained the Wilmot Proviso outlawing slavery in all new Western territories, the Southern congressmen showed fierce resistance, and this splitting bill quickened divisions between the two regions. Although the Compromise of 1850 attempted to reconcile those differences by backing the belief of popular sovereignty, whereby western lands had the right to conclude for themselves whether they would be free or slave states, the fight to inspire the decisions of territories populations on the slavery issued continued. Also, the existence of the Free-Soil Party as a movement opposed to slavery’s expansion in the late 1840s and early 1850s shows the influence of the slavery dispute on the nation’s politics. In addition, the
Gadsden Purchase of the Mesilla Valley in the Southwest for the construction of a southern continental railroad route powered the debate over whether the railroad should be built there or through free territory clarifying how crucial the slavery dispute was to both the North and South because each region unified to dominate the economic development of the West.
The Kansas-Nebraska Act and Dred Scott evaluation quickened the slavery dispute and emphasized tensions between the North and South, pushing the U.S. closer to the Civil War. In addition, the Kansas-Nebraska Act invalidated the Missouri Compromise of 1820, which had held the nation together by appeasing both regions, by tolerating slavery north of the 36’30 line. So, this law triggered an uproar in the North, leading to an progressively differentiated political environment in which neither side was willing to cooperation. Consequently, both pro-slavery and anti-slavery backers submerged Kansas and battled in the “Bleeding Kansas” conflict over whether the territory would be a free state or slave state. After the