Americans also like to make every historic victory sound like the entire conflict was about moral ideals and they were the flawless defenders of the Right Thing.
Interestingly the way people outside the US are taught about the American Civil War is far more nuanced: state rights, economical reasons, sovereignty, etc.
But I guess "the North declared war on the seceding South because the South was literally worse than Hitler" is a valid interpretation too. Teach the controversy, right?
Slavery.