Interestingly the border states of Maryland, Kentucky and Missouri were permitted to keep their slaves until the end of the Civil War even after the Emancipation Proclamation declared slaves in the southern states to be free in 1863.

The residents of the southern states had lived in fear of a mass slave uprising for decades before the Civil War. Some historians have speculated that Lincoln's Emancipation Proclamation was motivated more by a desire to promote this fear and to create instability in the Confederate States of America than by an abolitionist sympathy.

By the time Lincoln was elected seven southern states had already seceded. His soft position with respect to the above mentioned three states bordering on the Confederacy has given rise to a theory that he may not have pushed as hard for abolition if he was successful in securing the re-entry of the seven states to the Union and that slavery may have persisted for a longer period of time. The hesitancy of Delaware, Kentucky and Mississippi to ratify the 13th Amendment until well into the 20th century would seem to support this.