After the depression of 1837 in the South and the Indian removal, Americans had expanded their territory further in the West by the 1840s. The expansion in the land inspired the expansion of slavery. In the 1840s and 1850s, this expansion of slavery became the most divisive political issue since it caused the Texas revolt, made James K. Polk win the election of 1844, and brought disagreements over the Marxian War between Polk and politicians in the North.
The expansion of slavery led to the Texas revolt, which resulted in the independence of Texas. Texas was initially a part of Mexico. Since most of its residents owned slaves, Texas felt threatened when the governor of Mexico Santa Anna used his army to encourage the abolition of slavery in the region in 1835. In order to remain slaves, Texas built its provisional government to call for its separation from the Mexico. In April 1836, the army of Texas beat Santa Anna’s army to establish the Republic of Texas, which allowed the use of slaves in Texas.
In addition, the expansion of slavery enabled James K. Polk, the supporter of Texas annexation, to win the election of 1844, which caused the resent among the Democrats in the North. After separating from Mexico, Texas requested to become a part of America. By rejecting Texas to enter in the United States as a slave state, the candidate for president from Democratic partly, Van Buren lost his support in the slave states in the South. As a result, James K. Polk, who agreed on the Texas annexation, eventually won the election of 1844. Many Democrats in the South betrayed the Northern Democrats by voting for Polk to support Texas annexation, which caused the resent among the Northern Democrats. Furthermore, the expansion of slavery brought the criticisms of the Mexican War from some Northern politicians like Abraham Lincoln. In order to seize the land from Mexico, Polk