Answer: The Abolition Movement, The Election of Abraham Lincoln, and Economic and Social Differences
Explanation:
The Abolition Movement: The Northerners were against slavery and they began to fight against the system of slaves, becoming Sympathetic with them. They wanted to end slavery.
Election of Abraham Lincoln: The Southerners believed that Lincoln was against slavery and was biased towards the North. Therefore, seven of the states left the Union before Lincoln's presidency.
Economic and Social Differences: The Southerners mainly focused on slavery and farming lives, meanwhile the Northerners focused mainly on cities and the industrialization life.