The decision that split the country into slave states or free states, depending on their location. This helped split the country even more to the north vs the south.
The Texas annexation was the 1845 induction of Texas into the United States of America, which was admitted to the Union as the 28th state. Leaders of both major American political parties, the Democrats and Whigs) strenuously objected to introducing Texas, a vast slave-holding region, into the U.S, which obviously caused tension between those who apposed the state, and the south, who wanted the state.
An war between the United States and the Centralist Republic of Mexico from 1846 to 1848 in the wake of the 1845 U.S. annexation of Texas, which Mexico considered part of its territory. This probably opened some peoples eyes, that war was an option.
This law would have banned slavery in any territory to be acquired from Mexico in the Mexican War or in the future, which would include parts of Texas. With Texas becoming a new slave state in the south, they didn't want slavery to be taken out of it.
The Free Soil Party was a political party in the United States in the 1848 and 1852 presidential elections, and in some state elections. Its main purpose was opposing the expansion of slavery into the western territories, arguing that free men on free soil comprised a morally and economically superior system to slavery. Which made it a cause in starting the civil war.
Five separate bills passed in the United States in September 1850, which ended a four-year confrontation between the slave states of the South and the free states of the North regarding the status of territories acquired during the Mexican-American War.
This law states required that all escaped slaves were, upon capture, to be returned to their masters and that officials and citizens of free states had to cooperate in this law. Most of the North obviously did not want to return slaves to their owners.
A new party is founded in 1854, which goes strongly against slavery, the first president under this party was Aberham Lincoln. This was obviously seen as a threat to the south, having a whole new party in office, going against their slavery.
The ordinance made official that the northwest territory belonged to the U.S. But the area was to be slave free. This would have made slave owners who wanted to migrate angry.
The Kansas–Nebraska Act created the territories of Kansas and Nebraska, opening new lands for settlement, and had the effect of repealing the Missouri Compromise of 1820 by allowing white male settlers in those territories to determine through popular sovereignty whether they would allow slavery within each territory. Based on the settlers decisions, it would cause even more anger between the people.
A series of attacks between the north and the south on the borders of Kansas, which needed to decided whether or not it would be a free state. It was a site of early civil war, a "battle" before the war itself started.
The Supreme Court decided that and African American, free or slave, is not considered a citizen. Deed Scott was a slave who was taken to the free states by his owners, but when he went to court to be free, he was denied. This made abolitionists even more angry and was a catalyst for the civil war.
While the democrats were split between the north and the south, the republicans received the majority of electoral votes, putting Abraham Lincoln in the seat of the president. Lincoln was a strong abolishinism believer, this event is what finally lit the fuse on the beginning of the Civil War.
On December 20, 1860, South Carolina became the first Southern state to declare its secession and later formed the Confederacy. This is one of the main decisions that started the civil war.