Emancipation Proclamation
In 1863, the Emancipation Proclamation was put into effect and abolished slavery in states there were still in rebellion on January 1, 1863. Since these states were still in rebellion, it did not actually free anyone until the area was recaptured. This also meant that slavery was not abolished in the four border states that remained in the Union as well as any states that seceded that were willing to re-enter the Union.
Many scholars believe the Emancipation Proclamation was more a means to begin a movement instead of an actual end slavery.