Obviously slavery was deeply engrained within the Deep South and even Upper South as basis for the economy, but were there signals of reform in any of the border states which were less reliant on it for their economy, like Delaware? I read that in Delaware that about 90% of the blacks were free and of course geographically it's more connected to the North than the South so it would make sense. I'm curious as to what the prevailing attitudes were like at the time.
so where would the black people go? That's really the key problem with anti slavery arguments in the upper south and the appeal of colonization. Until you could seriously answer that question abolition didn't really have a chance, but if you could eliminate slavery and get rid of former slaves you would expose a real fault line in Upper south societies given many were a combination of mostly free white societies and slave aristocracies.
Post Nat Turner's revolt Virginia debated the future of slavery in 1831-1832 and came very close to banning slavery. There has been some good recent scholarship on this but to take an older (1980s) one:
t, “In providing a more detailed look at this dramatic episode in Virginia history, I hope to demonstrate that the 1832 Virginia slavery debate was not an isolated aberration, but rather part of an ongoing contest between a white community irrepressibly divided by slavery” (xii). As Freehling observes, the practice of slavery in Virginia intensified geographic divisions in the state, as the eastern Tidewater and Piedmont portions of the state contained the largest number of slaves, especially the “Southside” area next to North Carolina. Beyond the Blue Ridge Mountains in the Shenandoah Valley, the slave population declined drastically and was virtually non-existent west of the Allegany Mountains. The western counties of the state shared culture and trade interests with the free states of the Old Northwest rather than with eastern counties of the state, and this division only intensified during the antebellum period despite the efforts of political leaders to use internal improvements to unite the state economically.
I haven't read this book but it tracks with what i've read. Essentially to understand a slave state abolition you need to forget about black people and start thinking about how slavery impacted white society and there were some major cleavages in the border regions (and Delaware barely counts here given the microscopic size of its slave population. That + the fact i know very little about delaware specifically means i'm going to mostly ignore it). Controling slave populations and running a plantation based economy created real economic and political problems for the white farmer living outside of core slave country and these intra south dynamics are fascinating to look at.
http://personal.tcu.edu/swoodworth/GoodyearFreehling.htm
Bill Freehling in his recent books points out the fear of Upper south defections played a strong role in motivating the fire eaters to take their radical steps (and in earlier struggles it was the more moderate middle and upper south which forced an end to the crises). Yancy and co clearly thought given 10 20 years especially with republican patronage and postal services the upper south would break away and probably turn against slavery (esp. Delaware though the concerns were really more about states is MO). This isn't universally accepted but it does highlight how fears of abolition were real enough.
I would recommend Freehling's "road to disunion volumes 1 and 2"