What caused the American Civil War to break out? Was there one factor that caused more conflict leading to the American Civil War?

There were multiple factors that led to it.

The “stepping stones” that caused tensions to rise:
1: People in the North wanting to ban slavery.
2: People in the South wanting to keep slavery around.

The reasons that directly led to the war:
1: Abraham Lincoln being elected as the president of the US.
2: The South seceding from the North and making their own country.

because of SLAVERY

Explanation:

there were free and slave states, they wanted to prohibit slavery in land that wasnt considered a state yet

Americans had more steel, food, cloth, and coal than even the richest foreign nations. America's economic strength influenced its policies toward Europe during the 1920s. In fact, one of the most important issues of this period was the economic aid the United States had provided European nations during World War One.