Which Union areas were allowed to keep slaves as slaves?
Delaware and Kentucky. Maryland and Missouri had ended slavery within their states by state decrees.
Maryland, Delaware, Kentucky, and Missouri. I don’t know about West Virginia.
“Which Union areas were allowed to keep slaves as slaves?”
It’s not that they were ‘allowed’- slavery was legal in the United States until the 13th Amendment passed. Individual states could outlaw the practice within their borders, but the national government had to follow the law in order to make slavery illegal on a national basis. Lincoln wasn’t a king who could rule by decree.
The emancipation proclamation was implemented against people whom Lincoln regarded as outlaw American citizens. I guess asset forfeiture is our closest modern equivalent. He regarded the Confederacy as a fiction much like King George regarded colonial claims of independence as fiction.
People posting here who think that civil war is an acceptable method for a politician to change law and custom should think about what they’re saying. It’s basically Obama’s executive orders plus bullets for those who object.