While human slavery was an enormous issue in the United States since its inception, the country managed to go almost a hundred years without resolving the issue either through abolition or full legal acceptance of slavery. In fact, until the outbreak of war, American politicians had skillfully negotiated compromises in almost every domestic issue of the day to prevent slavery from driving a wedge between the states. Although conflict was inevitable in retrospect, for almost a century politicians had every reason to believe otherwise.

Early Compromises: The Constitution

Many early political compromises around slavery revolved around the outsized importance of Southern states in the early American economy. Slavery was largely concentrated in the South, but the South was also a major economic force that was the engine of growth in the new country. Northerners wanted to abolish slavery, but were unable to include anything that might prevent the South from adopting the Constitution and jeopardize the new Union.

Two significant compromises regarding slavery were included in the Constitution. The first, the infamous “three-fifths compromise”, concerned political representation. Seats in Congress were allocated according to population, and the Southern states wanted their slaves to be counted among the population in order to give them more seats. Northern states argued that this was unjust, since those slaves were unable to vote or otherwise participate in political life. The South countered that without the additional seats they would be outnumbered in Congress, and refused to budge. The end result was to count the slaves as part of the population, but only as ⅗ of a free person.

The second slavery debate surrounding the Constitution concerned the practice of importing new slaves. While the whole country had yet to accept that slavery itself was barbaric, news had spread of the horrors of shipping slaves across the ocean. As a result, several states had not banned slavery, but had banned the importing of new slaves from overseas. With a new Constitution, slaveholding states were concerned that the Congress would have the power to ban the import of slaves, the first step towards outlawing slavery as a whole. Rather than find a way to make both parties happy, the participants at the Constitutional Convention simply decided to put the question off to a later date. The Constitution grants Congress the power to ban the import of slaves if it so chooses, but only after 1808, almost 30 years after its adoption.

Amazingly, with these two provisions, the Constitution was ratified in both the South, where ratifiers argued it preserved slavery, and the North, where some argued it laid the groundwork for its eventual abolition. Because of the importance of the issue, almost every provision in the Constitution was drafted with slavery in mind, although few as explicit as the two above. After ratification, only six of thirteen states allowed slavery.

Tensions Grow: American Expansion and Slavery

Shortly after the Constitution was ratified, the cotton gin was invented and the importance of slaves to the Southern economy grew enormously. The drastic increase in the number of slaves and the dehumanizing treatment they were subjected to thrust the issue back into the national spotlight. At the same time, the delicate compromises of the Constitution were threatened by a new problem: the admission of new states to the Union.

As new states were added, they were given two seats in the Senate and proportional seats in the House. Each new state added thus threatened to tilt the balance either towards abolition or to permanent slavery. In the years after the Constitution was ratified, the Congress was careful to admit the creation of new states only in a way that would maintain that balance. New slave states such as Kentucky, Tennessee, or Louisiana were counterbalanced with new abolitionist states, such as Vermont, Ohio, and Indiana. While the populations of these states varied, each state is entitled to the same number of Senate seats, guaranteeing deadlock on the issue of slavery.

During the half century before the Civil War, American territory expanded across the continent at a fantastic rate. Citizens of these territories wanted the protection and political representation that came with statehood, and frequently petitioned Congress to admit their territories as new states. Because of the slavery issue, Congress frequently split these territories into multiple states, and drew new borders to prevent one faction from gaining too much power.

The Missouri Compromise of 1820 is the most famous example of the deadlock and the fight to preserve it. America had purchased the Louisiana Territory from France, a large block of land in the southern United States next to Texas. Missouri, a parcel within the territory, applied for statehood. The bill to add the state to the Union quickly had an amendment added that required Missouri and the entire Louisiana territory to ban slavery before being admitted. The bill was debated extensively and admission for Missouri seemed hopeless until Maine, a territory in the Northeastern United States also applied for statehood as a non-slave state. Speaker of the House Henry Clay brokered a compromise to consider both applications together. With pro-slavery Missouri counterbalanced by anti-slavery Maine to preserve the stalemate in Congress, the proposal was approved.

While the main battle was over control of the Senate, there were other fights and compromises on the issue of slavery. In a federal form of government, clashes over domestic issues frequently turn into clashes over the relative power of local and federal government. This was the case with slavery as well: the federal government wanted to abolish slavery, so slave states insisted that it was not within the federal government’s power to do so.

Although they have sovereignty, the Constitution requires that individual states adhere to laws passed by Congress. This does not extend in the other direction: individual states have no authority over the United States Congress. Slaveholding states were worried that Congress would pass measures restricting slavery, and so decided to invent authority over Congress. This was called “nullification,” the theory that an individual state could pass a law declaring an act of Congress invalid within their borders.

The main clash over nullification played out over a tariff, although all sides knew that the tariff was a testing ground for nullifying federal slavery laws. The state of South Carolina declared that the Tariff Laws of 1828 and 1832 were unconstitutional, and invalid within the state. While tariffs are allowed under the Constitution because Congress has the power to regulate commerce, South Carolina argued that they were overly protectionist, and thus went beyond the scope of the Constitution.

Both the Federal government and South Carolina prepared for military conflict to enforce their decisions. Rather than go to war, however, President Jackson negotiated a compromise with South Carolina. Congress would lower the tariff rate if South Carolina would concede to the superiority of Federal law. Northern states would also later attempt to nullify laws requiring them to help locate and return escaped slaves, with the same outcome.

The Dam Breaks: Secession and the End of Compromise

As more non-slave states were admitted to the Union and popular opinion turned against slavery, the end of compromise became inevitable. The South no longer had the political bargaining power to match the North. Events came to a head in the election of 1860, when Abraham Lincoln ran on an explicit platform of outlawing slavery. Once he was elected, the possibility of further compromise was closed and the Southern states seceded.

For more than 80 years the fledgling republic managed to remain intact despite the growing political cleavage, through a series of compromises that ensured no one side in the slavery debate could gain decisive advantage to either ban the practice or to ensure that the issue would be put to bed. After the war, the 13th Amendment to the Constitution banned slavery, eliminating the three-fifths compromise. The 14th Amendment established limitations on the power of individual states to violate civil rights, ending some of the compromise on states’ rights.