There are many key issues that caused the American Civil War. They all mainly deal with disagreements between the North and the South. In the North, slaves were now free. They still faced a lot of discrimination, but they were happy to be free from slavery.
The Missouri Compromise
One of the significant issues that started the Civil War was Missouri becoming a slave state. In the early 1800s, Southern slave owners wanted slavery to spread into Western territories. A lot of the North states were against this idea because they wanted to reserve this land for White settlers. Each time territory reached 60,000 inhabitants, it would become a state and enter the country; it would decide if it wanted to be a slave state or a free state. When Missouri entered, it decided it wanted to be a slave state, which the Union was incredibly angry about. This was because there were 11 free and 11 slave states at the time, and the Union was against adding more slave states. Finally, a compromise was made. In 1820, Maine was ready to be a state and was admitted as a free state. Over a year later, Missouri was finally admitted as a slave state.
The Compromise of 1850
After the U.S. won the Mexican-American war, the same issue happened again. California was ready to be admitted as a state and wanted to be a free state. Southerners were afraid that the number of free states would soon greatly outnumber the number of slave states. Congress feared that if Congress did not allow slavery in new territories, they might even abolish it in places where it already existed. In 1850, another compromise (the compromise of 1850) was reached. California was admitted as a free state, and slave trade was abolished in Washington D.C. This was what the North gained out of it. The rest of the land gained from Mexico was divided into Utah and New Mexico, which allowed slavery.
The Confederacy
In 1854, Congress passed the Kansas-Nebraska act, which allowed settlers to determine their own slavery laws instead of Congress. In 1858, two important men who both wanted to be Senator debated over the topic of slavery. These men were Stephen A. Douglass and Abraham Lincoln. Lincoln was not as well-known as Douglass and lost the debate when Douglass said that Lincoln supported equality for Black Americans. Lincoln lost the debate but ended up getting elected for president. There was a major problem with this, however. Many of the southern states declared that if a republican like Lincoln was elected for president, they would secede. South Carolina did exactly that with Mississippi, Florida, Alabama, Georgia, Louisiana, and Texas following six weeks later. These states became the Confederacy and elected Jefferson Davis to be their president.
Conclusion
In the following paragraphs, I explained some significant issues that started the American Civil war. There were issues between states, economic issues, and issues between power. These all led to the war as we know it today.