This was brought up recently by Sadseh, but his thread is now in the bug forum, since I want people to see this I'll post this here:
"Slavery Hotly Debated In xxx" edited so that they cannot appear after the Civil War.
Bleeding Kansas will not happen after the ACW
Lincoln Asassinated can happen even if he was not elected
Reconstruction fires asuming the ACW event was fired and the USA and CSA are not currently at war.