Slavery was legal in several border states that did not join the rebellion, and the Emancipation Proclamation did not cover areas that were not in rebellion. Kentucky, Maryland, Delaware and Missouri were all states that had legal slavery until the passage of the 13th Amendment after the Civil War. West Virginia was in a special category in that it had been part of a slave state until 1863, when it became a state of its own and joined the Union. The District of Columbia had slavery until January, 1863.
Because it allowed slavery to continue in the Border States - slave-states of the Upper South that had stayed loyal.
Lincoln allowed slavery to continue there - so as not to drive those states into the arms of the Confederacy.
When Abraham Lincoln called for troops to march south to recapture Fort, second-class citizenship for blacks, although they were still legally allowed to vote.
Short-term, nothing - slavery was allowed to continue in the slave-states that had remained loyal. Long-term, the loyalty of these states helped the Union to win the war - which is what brought slavery to an end throughout the USA.
emancipitation
Vermont was the first state in the United States to abolish slavery in its constitution in 1777. Other states that never allowed slavery include Massachusetts, New Hampshire, and Pennsylvania.
Only one state was allowed to stay neutral, and that wasn't for long. It was Kentucky - one of the four Border states that were allowed to continue practising slavery for the duration of hostilities. But it was on condition that they stayed loyal.
Because it allowed slavery to continue in the four slave-states that had stayed loyal (Kentucky, Missouri, Maryland, Delaware).
They were the slave-states that stayed loyal to the Union. Lincoln treated them tactfully, and allowed them to continue practising slavery during hostilities, for fear of driving them into the arms of the Confederacy.
An American state where slavery was not allowed by law was called a "free state." These states did not permit the practice of slavery within their boundaries, in contrast to states where slavery was legal.
The four states that allowed slavery was Missouri,Kentucky,Maryland,Delaware and that is from my The American Journey-Building A Nation
all accept the northern states