A pair of quotes to consider concerning the infernal sin of chattel slavery....
-Ellsworth: All good men wish the entire abolition of slavery, as soon as it can take place with safety to the public, and for the lasting good of the present wretched race of slaves. The only possible step that could be taken towards it by the convention was to fix a period after which they should not be imported. - The Landholder, 1787
-Madison: It is due to justice; due to humanity; due to truth; to the sympathies of our nature; in fine, to our character as a people, both abroad and at home, that they should be considered, as much as possible, in the light of human beings, and not as mere property. As such, they are acted upon by our laws, and have an interest in our laws. - speech to the Virginia Ratifying Committee, 1829
To be fair, no history of America can be complete unless we discuss the horrid institution of slavery and in this respect, Nikole Hannah-Jones' 1617 works have to be included, for all its errors. But contrary to popular liberal convention/opinion, slavery was a dying institution across the Western world; but for Eli Whitney's invention of the cotton gin, slavery might've died out prior to the Civil War.
Contrary to popular opinion, slavery was already on ita' way in the Americas; Mexico abolished it around 1824, most of the former Spanish colonies in Latin & South America abolished it in the first decades of the 1800's as the various Wars of Independence raged on while Upper Canada (Ontario) abolished it in 1819. (Lower Canada, a/k/a Quebec, had never allowed it either before or after British capture of New France following the Seven Years' War).
Even slaveholding Founders' such as George Washington and Thomas Jefferson recognized that at some point the infernal institution would end; Jefferson led the fight to pass the Slave Trade Act, which codified into statutory law Article 5, Section 2 the prohibition on importation of slaves into the United States (which ironically was enforced mostly by, of all countries, the United Kingdom via' the Royal Navy's Africa Squadron. Even the provisions considered "pro-slavery" - in particular, the three-fifths clause - eventually became logic bombs in the South as more and more slaves arrived because it stilted population numbers in the South vs. their Northern counterparts.
Eventually, though, it took a Civil Wart to end it across the United States, a war fought by the Republican North against the Democratic South (remember, it was the Democrats' who defended slavery, Democrats who defended Jim Crow, Democrats who defended racial segregation following Reconstruction, etc.