How did slavery monopolize politics and elections between 1820 and 1860?
Slavery began to take up more of the national debate when the institution became more lucrative, thanks to increased Western settlement and the invention of the cotton gin, which allowed slaves to be even more productive. Starting in 1820, there was fear in slaveholding circles that Northern abolitionist senators would one day outnumber Southern senators. The fear was that slavery would one day be limited and abolished. Henry Clay came to the rescue in 1820 with the Missouri Compromise which allowed Maine to enter in as a free state in order to counterbalance the admission of the slave state of Missouri. It was also decided at that point that all lands south of Missouri would be slave states and all lands north of Missouri's southern border would be free.
The admission of Texas would also be another focal point in the slave debate as Northern abolitionists, now more organized and with newspapers such as The Liberator to help spread their message, protested when Texas was to be admitted as a free state. As a result, the decision was put off until John Tyler decided to make it a focal point of his presidency in order to win over votes. While Texas was eventually admitted, the decision made Tyler hated in Northern abolitionist circles. The decision to go to war with Mexico was also shaded by the slavery question as the war was launched by a Southern president, James Polk of Tennessee. After the war, Southern congressmen also questioned the possibility of buying Cuba from Spain in order to add another slave state to the Union. This made Northern abolitionists fear that there was a slaveholding minority who wished to control the national agenda. This only made abolitionists fight harder in their attempt to limit slavery's spread in the United States. The Compromise of 1850 marked a watershed moment in the slave question when Congress decided the fate of the newly acquired Mexican Cession, as well as strengthened the Fugitive Slave Law. While this all passed in order to bring peace to both sides of the issue, no one was really happy with the compromise. Stephen Douglas further upset the balance when he authored the Kansas-Nebraska Act in order to hurriedly bring Kansas into the Union. He stated that the people of the territories could decide whether or not they wanted slavery –– this overturned the Compromise of 1820 and led to Bleeding Kansas, a guerrilla free-for-all which took place on the Kansas-Missouri border before the Civil War.
The slavery question also helped to give birth to the Republican Party. One of the party's earliest planks was to limit the spread of slavery into the territories. It was formed from conscientious Whigs who supported the Whig platform but hated the idea of slavery. Some of the most prominent early members of the party were William Seward and Abraham Lincoln. Another early anti-slavery party was the Liberty Party, led nationally by James Birney. While Birney stood little chance of winning an election, he offered an alternative choice for people who wished to vote for president but could not endorse a pro-slavery Whig or Democrat.
Slavery began to cast its shadow upon American politics when it threatened to upset the balance of power in the Congress. When Missouri territory applied for statehood the question of slavery became front and center. At the time (1819-1820) there were 11 free states and 11 slave states, in other words, the political status-quo was preserved. However, if Missouri were to enter the union as a slave state the balance would be shifted. A compromise was established by allowing Missouri to enter the union as a slave state and Maine would enter as a free state, unfortunately this was not a solution, it was a band-aid on a cut that kept on bleeding. This is evident in the Compromise of 1850 which continued to 'appease' the powers that be. The Kansas-Nebraska Act of 1854 which suggested popular sovereignty fueled the fire between the north and south. Proslavery antagonists were pitted against the political free-soilers in Kansas that by the 1857 election the ballot was little more than a contest between slavery or no slavery. The Supreme Court decision in the Dred Scott case only added to the tensions between the federal-state relationship. President Buchanan was at a loss as to promote a solution which resulted in 'the point of no return'. By 1859 abolitionist John Brown cast the final blow. His militant plan to promote a slave uprising failed and resulted in his conviction of treason. The 1860 election represented the total break down between opinion, politics, and the election. South Carolina stated if Lincoln were elected they would secede from the union. He was elected, they did secede and the rest they say is history. American politics between 1820 and 1859 was gagging on the issue of slavery, by 1861 it began to choke to death.
The battle over slavery was also the battle over sectional power. In 1820, the Missouri Compromise created a delicate balance between slave and non-slave states by creating Missouri as a slave state and by carving the state of Maine out of Massachusetts to make a free state. The border between slave and non-slave states was created at the 36°30' line of latitude.
In the early 1800s, much of the North became increasingly abolitionist, in part because the attitude of reformers had turned against slavery and in part because they were worried about the growing power of the South. The South, for its part, became increasingly committed to slavery after the cotton gin made growing cotton more profitable and easier. Each election from 1820 until the election of Lincoln in 1860 was an attempt by different sections of the country to maintain their grasp on national power by either limiting slave states (in the case of the North) or by increasing the spread of slavery (in the South).