Final answer:
Southern states felt threatened by being surrounded by states with low slave populations due to their economic reliance on slavery and the associated risks of rebellion and loss of political influence.
Step-by-step explanation:
The fear that southern states had regarding being surrounded by states with low slave populations stemmed from both economic and social concerns. In the period leading up to the Civil War, the southern economy was heavily dependent on slavery to support the plantation system, particularly the production of cotton. The pro-slavery ideology held that slavery was essential for the economic stability of the South and that, without it, there would be significant risks of insurrection and social discord.
The possible expansion of slavery into new territories was a contentious issue. Areas such as Utah and New Mexico allowed slavery but had low levels of slaveholding, which did little to assure the southern states about maintaining their influence within the national government. Conversely, the Upper South, including states like Virginia and Maryland, possessed a surplus of slaves and saw economic opportunity in the internal slave trade.
Fears of a rebellion among the nearly four million slaves, potential restrictions on the international slave trade, and the consequences of a hostile northern majority in Congress further fueled southern anxieties. When tensions reached a breaking point with the assault on Fort Sumter, eleven states ultimately formed the Confederacy, founded on the preservation of slavery. This perceived threat to slavery from low-slave-population states was a driving force behind the secession of the southern states and the ensuing Civil War.