The history of slavery dates back to ancient times and has persisted through the centuries. It began as an economic system in which people were either bought or sold as property. The ancient Egyptians, Babylonians, Greeks, and Romans all practiced some form of slavery, and by the 1600s, it had spread to the American colonies. Slavery was rooted in the economic inequality of the time, and in many cases, it was used to fill labor gaps created by agricultural expansion and other economic pursuits. Slavery in the United States peaked in the mid-19th century, when nearly 4 million African Americans were enslaved. Slavery in the United States was eventually abolished in 1865 after the passage of the 13th Amendment to the U.S. Constitution. Unfortunately, the legacies of slavery still persist in many forms today.