I picked up American literature volume 1, the Norton anthology at a book exchange. Anyways it's comprised of letters from Christopher Columbus (1493) and Hernan Cortez (1519) all the way to Harriet Prescott spofford (1860).
Well about two thirds into the book the abolitionist movement happens and while most of the texts are pro abolition there are a few such as Harriet Jacobs (though a slave) and Lydia Maria child (though a coal burner)
I lost the point I was trying to make out of all the abolitionist there was 0 proslavery as this book was meant to be taught in universities. (Though it should be both sides of the story) I find that the south didn't have as much access to printing presses as compared to the northeast.
There are some very good abolitionist writings however, that you should check out: the Meaning of July Fourth for the Negro by Fredrick Douglass 1852
Herman Melville Benito Cereno
Henry David Thoreau Slavery in Madsachusetts
I'm no pro abolitionist but they do dig into some root causes of slavery and remedies