Must have been surprising to the Native Americans being slaughtered and sent to reservations and all the immigrant labor being exploited to make those railroads as well. America is the land of the free for the upper caste.
Founding Fathers, who were mostly abolitionists: “Slavery is surely a dying institution, we can just put it on the back burner and let it wither away, that way we can avoid a civil war.”
In their meager defense, they were correct at the time, slavery was a dying institution. It wasn’t until the later invention of the cotton gin that slavery exploded in profit. By then, it was too late. The economic interests of the slavers had grown and entrenched, and the war became inevitable.
Not to defend the slavers, or their advocates among the founders, just to explain the founders’ reasoning a little more.