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The Kansas-Nebraska Act and party realignment

The Kansas-Nebraska Act, passed in 1854, reopened the debate over the expansion of slavery  in the United States.


  • The Kansas-Nebraska Act organized two new territories in the land acquired through the Louisiana Purchase, Kansas and Nebraska. The act established that in these territories, the principle of popular sovereignty would apply, meaning that the white residents of each territory would vote on whether to permit slavery when applying for statehood.
  • The Act repealed the Missouri Compromise of 1820, which drew the horizontal line of slavery across the West along the 36° 30' parallel, as both Kansas and Nebraska were north of this line. This reopened the question of slavery’s western expansion.
  • The passage of the Kansas-Nebraska Act induced party realignment and violence, furthering the sectional divide that ultimately erupted in the Civil War.

The Kansas-Nebraska Act and popular sovereignty

In 1854, an uproar regarding the question of slavery in the territories challenged the relative calm after the Compromise of 1850. The pressure on this question came primarily from northern farmers, who wanted the federal government to survey the land west of Iowa and Missouri and put it up for sale. Promoters of a transcontinental railroad also pushed for this westward expansion.
Furthermore, many in the South were growing resentful of the Missouri Compromise, which established the 36° 30' parallel as the geographical boundary of slavery. Slaveholders entrenched themselves in defense of their “way of life,” which depended on the ownership of slaves, while also claiming that prohibiting slavery’s expansion ran counter to basic American property rights. They now contended that the question should be decided by popular sovereignty, or allowing the white residents of a territory to decide whether it should permit slavery when it applied for statehood.
Meanwhile, some antislavery northerners wanted the West reserved for poor whites to seek opportunity. Abolitionists, too, were becoming more vocal in their support for the complete end of slavery.
Democratic leaders sought to bind these disparate ideologies together. Illinois Democratic senator Stephen Douglas believed he had found a solution—the Kansas-Nebraska bill—that would promote party unity and also appease Southerners who detested the Missouri Compromise line. The act created two territories: Kansas, directly west of Missouri; and Nebraska, west of Iowa. The act applied the principle of popular sovereignty. Since both territories fell above the 36° 30' line, the proposed bill would repeal the Missouri Compromise of 1820.
After heated debates—many members carried a concealed revolver or a knife to the sessions—Congress narrowly passed the act.

Party realignment

The passage of the Kansas-Nebraska Act, which allowed residents of Kansas to determine whether the state would be slave or free, sparked a violent struggle between proslavery and antislavery factions, both of whom flooded into the territory hoping to gain enough votes for their side to triumph. It also spurred a major party realignment.
Since the 1830s, the two main political parties in the United States had been the Democratic Party and the Whig Party. The parties disagreed mainly about economic policy. Whigs advocated for accelerated economic growth, often endorsing federal government projects to achieve that goal. Democrats wanted the federal government to play a smaller role in regulating the economy. Whigs tended to be wealthier; they were prominent planters in the South and wealthy urban northerners--in other words, the beneficiaries of the market revolution. Democrats presented themselves as defenders of the common people against the elite.
The issue of slavery began to crack the foundations of the Second Party System in the 1840s. The Kansas-Nebraska Act divided the Democratic Party along sectional lines, as half of the northern Democrats in the House voted against it. In 1848, the newly-formed Free Soil Party nominated former president Martin Van Buren and ran on an antislavery platform of “Free Soil, Free Labor, Free Men.”
The Democrats divided along sectional lines as a result of the bill, and the Whig party, in decline in the early 1850s, found its political power slipping further. Most important, the Kansas-Nebraska Act gave rise to the Republican Party, a new political party that attracted northern Whigs, Democrats who shunned the Kansas-Nebraska Act, members of the Free-Soil Party, and assorted abolitionists.
As a result, the Republican Party became a solidly northern political organization, creating a new binary party system reflecting sectional fault lines along the question of slavery.

What do you think?

Imagine you were a Northern abolitionist when the Kansas-Nebraska Act was passed. How would you respond?
Explain how the two-party system shifted at the end of the 1850s.
How did the new party system differ geographically from the Second Party System?

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