What was the cause of the United States Civil War?

Nikki Haley Wednesday night: "I think the cause of the Civil War was basically how government was going to run, what you could and couldn't do, the freedoms in what people could and couldn't do."
Nikki Haley Thursday morning: "Of course the Civil War was about slavery, that's the easy part"
reuters.com - Nikki haley asked about cause US civil war declines mention slavery

Out of curiosity, I ran this by ChatGBT. Summary of ChatGBT 3.5 answers in different speaking styles:
ChatGBT: The most significant and divisive issue was slavery.

guess of what Abraham Lincoln might say: The primary cause, without question, was the institution of slavery.

guess of what Biden might say: There's no denying that the root cause was slavery.

guess of what Haley might say: There were issues of states' rights, economic differences, and yes, slavery was undeniably a deeply divisive issue.

guess of what Jefferson Davis might say: The War Between the States, as we often term it, was fundamentally about states' rights and the principles of self-governance. Yes, slavery was an important part of our economy and society, but it was a matter of states' rights—the right to govern ourselves as we saw fit within the framework of the Constitution.

guess of what Trump might say: It was all about states' rights. Now, some people say it was about slavery, but you know what? There were good people on both sides.