The first action that started the end of slavery was Abraham Lincoln signing the Emancipation Proclamation. This made having slaves illegal in the U.S. They would have to return the slaves to freedom on January 1, 1863 and President Lincoln also named ten states that would have to apply. This was put into the U.S. Constitution under Section 2.
The biggest step toward ending slavery was America's Civil War. The Civil War had a huge impact on slavery. If the North won slavery was soon to end. But, if the Confederates won then slavery was to go on for a longer time then it should. But as we all know the Union won and slavery became even closer to ending.
Even with the end of the Civil War slavery was still something to work on. Even with all the rules, compromises, proclamations, and bills there was a certain kind of slavery still going on. Blacks had to work to stay alive and keep there family's alive too. They worked, but were payed unfairly. They wouldn't make as much as a normal white man would.
Even whites could be like slaves. If they were beaten or whipped they could be like a slave. These 'slaves' were making money but could be beaten, whipped, slapped, etc. Slavery is an ongoing thing that needs to be dealt with before it is out of hand.