Delaware a border state:
http://www.lib.udel.edu/ud/spec/exhibits/lincolndelcivilwar/As Maryland, birthplace of John Wilkes Booth, Missouri, birthplaces of the James' brother, skirmishes with Abolitionists, the Jayhawkers in Kansas; Kentucky, in the news about having confederate monuments there. Sure, a Union state.
New Jersey, slow abolition of slavery, hardly any existed by the Civil War:
https://en.wikipedia.org/wiki/New_Jersey_in_the_American_Civil_WarSo, those are rather pernicious statements to insist "there were plenty of slaves in the North",
Too bad, these threads get hijacked with some pipe dream that will never happen and a debate on the civil war.
No state would have the right to order the murders of all of some segment of their populations, let's say Mormons for instance. This is a moral wrong. Slavery was a moral wrong but this facet is glossed over by defenders of the Confederacy.
Yes, we have modern moral wrongs indeed and it is a bit of a civil war as well.
The Union had every right to preserve the union itself; the Southern States list in their articles of secession, over and over again, they fought to preserve slavery. New Jersey was already abolishing it, Delaware was a border state. I will go with historians, not off-the-wall versions of history.