What were the main issues that caused a division between the southern and northern states of the USA?

Following were the main issues that caused a division between the southern and northern states of the USA:

1. Difference in Economic Structure of the Northern and Southern States — The Northern States were industrialised with developed infrastructure. Hence, the Northern states wanted to impose tariffs on imported goods to protect their industries from foreign competition. On the other hand, Southern States were primarily agricultural with huge plantations. Hence, they wanted tax-free trade with Britain to get cheap manufactured goods in exchange for raw cotton. This economic disparity between the North and the South created friction between the two.
2. Problem of Slavery — Slavery was abolished in the Northern States and they became free states. This was resented by the Southern States whose economy depended on slave labour.
3. Territorial Expansion — As the population of existing colonies increased, new colonies were explored in the western regions of North America. These newly settled colonies were absorbed into the USA as new states. The Northern States wanted these new states to be free states whereas the Southern states wanted them to be slave states.
4. Fear of Republican control — In 1860 Presidential elections, Abraham Lincoln as Republican candidate stood for freedom and emancipation of slaves while Stephen Arnold Douglas, the democratic candidate wanted slavery to continue. The Southerners fearing Lincoln's win decided to quit the Union. The Seven Southern states, namely South Carolina, Mississippi, Florida, Alabama, Georgia, Louisiana and Texas declared their secession from the Union and established a Southern government, the Confederate States of America on February 9, 1861 and elected Jefferson Davis as its President.