There were different causes of the Civil War, but the main one was slavery. The South needed slaves to work on farms and plantation. The north believed that slaves should be free.
Another reason for the war was the question of state rights. The South felt that the state should have the most power in government matters, but the North felt that the federal or national government should have the most power.
The third reason based on the economy. There were a lot of plantations in the South and slave labor was needed. The North had a lot of factories and used free labor.
The election of Abraham Lincoln caused the South much concern. President Lincoln did not believe in slavery and southerners felt that he did not support their interests.
An abolitionist movement began which spoke out against slavery and worked to free slaves. Many people turned against slavery and slaveholders as a result of this movement.
Finally, a tax was placed on imported goods or goods coming into the country. Since the tax was so high, it forced Southerners to buy goods from the North. This made the Southerners angry.