The Civil War was fought between the Confederates (North) and the Union (South)
In the mid-1800s, the economies of many northern states had moved away from farming to industry. A lot of people in the North worked and lived in large cities like New York, Philadelphia, and Boston. The southern states, however, had maintained a large farming economy and this economy was based on slave labor. While the North no longer needed slaves, the South relied heavily upon slaves for their way of life.
The idea of states' rights was not new to the Civil War. Since the Constitution was first written there had been arguments about how much power the states should have versus how much power the federal government should have. The southern states felt that the federal government was taking away their rights and powers.