Slavery ended when President Abraham Lincoln delivered his iconic Emancipation Proclamation. This would eventually free black people so they could become ordinary citizens and NOT slaves. So basically, slavery was ended all thanks to good ol' Lincoln :)
If you’re looking for what actually started the motion to end slavery (in England), it was a man named John Brown. His method was arguably not the best (he raided a place where lots of black slaves were being kept, which resulted in a few deaths) however it certainly helped abolish slavery.
New marketplaces and commercial links arose as a result of the Revolution. The triumph of the Americans also opened the western areas to invasion and colonisation, resulting in the creation of new domestic markets. Americans began to develop their own manufacturers, no longer relying on those in the United Kingdom.