Civil War Era

The westward expansion of the United States not only exacerbated tensions over slavery but also played a significant role in precipitating the Civil War. The process of admitting new states into the Union often involved significant concerns about maintaining a balance between free and slave states. Initially, the Ohio River Valley served as a natural boundary between the North and the South. However, westward expansion gradually eroded this clear division between the free North and the slaveholding South.

 

Prior to 1818, the balance of power in Congress was shared between free states and slave states. When Missouri applied for statehood, however, it raised concerns about maintaining the balance of power in Congress, as there was no free state prepared for admission to counterbalance the addition of another slave state. Tensions rose as a result and a temporary solution was reached with the Compromise of 1820, which admitted Missouri as a slave state while Maine entered as a free state, thereby preserving the balance. Additionally, the compromise established the 36°30' parallel as a boundary for slavery where the institution was permitted. The act was eventually overturned by the Kansas-Nebraska Act of 1854, which allowed settlers in those territories to decide the slavery issue through popular sovereignty. 

 

The addition of Texas further complicated matters. Anglo-American settlers began moving into Texas shortly after Mexican independence allowed Texas to become a part of the newly formed Mexican Republic. Mexican officials viewed anglo-American settlement as inevitable and proactively welcomed these ranchers and farmers on terms favorable to Mexico. 

Overtime, however, tensions grew between the Anglo settlers and the Mexican government over issues of immigration, local autonomy, and slavery. The Texas Revolution beginning 1835 sought to address these issues and culminated in the following year when the Republic of Texas was formed. 

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Texas struggle to establish itself as an independent nation from Mexico and sought U.S. annexation. The delay of Texas's admission to the Union until 1845 stemmed from apprehensions about disrupting the equilibrium between free and slave states in the union. Thus, Texas remained independent for a decade before its annexation, a move expedited by president James Polk's (1795-1849) recognition of potential free states in the Northwest, namely the Oregon territory. 

 

The ensuing  Mexican-American War (1846-1848) only made matters worse. Perceived as a fulfillment of Manifest Destiny, the war intended to obtain full control of the continent ended with the Treaty of Guadalupe Hidalgo in 1848. The treaty promised citizenship to Mexicans as the U.S. received the lands that included present-day California, Nevada, Utah, most of Arizona, New Mexico, Colorado, and Wyoming. However, the threat over extending slavery into the newly acquired territories continued to exacerbate tensions between the North and South. 

 

One example of lasting tensions emerged with the admission of California into the Union. California's bid for statehood as a free state prompted further debates that culminated in the Compromise of 1850. The legislative move introduced popular sovereignty to determine slavery in new territories and strengthened the Fugitive Slave Act, compelling northern citizens to participate in slave trade enforcement or face penalties. The legislation inspired Harriet Beecher Stowe to pen her most famous novel, Uncle Tom's Cabin, which was heavily influenced by the events unfolding in Congress during this period. Along with other abolitionist literature of the period, the work humanized the plight of the enslaved and stirred widespread empathy and outrage among Northern readers, serving for many as a catalyst for the Civil War.  [1]

 

Further legislative acts that dehumanized black Americans fueled tensions between the North and the South.  In 1820, Dr. John Emerson, an army surgeon, had moved to Illinois from the south taking with him Dred Scott, an enslaved worker. After Emerson’s death in 1843, Dred Scott attempted to purchase his freedom from Emerson’s widow, Irene Sanford. When she refused, Scott and his family sued for their freedom in a Missouri state court, arguing that their residence in free territories had made them free. When the case finally reached the Supreme Court in 1857, the landmark decision of Dred Scott v. Sanford ruled against Scott. Declaring that black Americans, whether free or enslaved, were not citizens and therefore had no standing in federal court, the Court ruled that Congress did not have the authority to prohibit slavery in the territories. In his ruling, Roger Taney indicated that white slave owners, by virtue of their citizenship to both the state and the nation, were not to be restricted to a geographic region due to the nature of their property. In effect, the ruling overturned years of compromise extending slavery, in effect, to the entire nation. 

 

In summary, westward expansion deeply intertwined issues of slavery, statehood, and racial dynamics, ultimately contributing to the growing tensions that led to the Civil War. Together with the Dred Scott decision, racial tensions over slavery rose to a boiling point as a new election cycle was underway.