What slave states did not secede from the union?
There were four slave states that did not secede from the union, Missouri, Kentucky, Maryland, and Delaware. Slaves in these states were not freed till after the civil war; not even by the Emancipation Proclamation.
There were five slave states that remained in the Union. Initially there were four -- Delaware, Maryland, Kentucky and Missouri. West Virgina separated from Virginia when it (Virginia) seceded from the Union. West Virginia was admitted to the Union in 1863 as a slave state. West Virgina remained in the Union making it the fifth slave state not to secede. These five slave states were called border states.
When all of the Confederate states became solidified as one collective rebellion, there were 15 slave states in the US. Of the fifteen, four slave states did not secede. Nineteen were free states. Thus as the war was fully underway, there were eleven Confederate states and 23 Union states. The slave states that did not secede were called "Border States". These were Delaware, Maryland, Kentucky and Missouri. Only the latter three states played a roles…