African slave trade started in Ghana and Nigeria during the 18th century. Slavery was a prime source of commerce. African slaves did have the ability to purchase their freedom after working a number of years.
Outside of Africa, the use of slaves became prominent in Portugal and the Carribean. Eventually slavery moved into South and Central America and then in the America. Interestingly, the development of slaves in America was on a smaller scale than the rest of the world. Once 4.4 percent of slaves ended up in America.
''The earliest records of the African slave trade in America date back to the beginning of the 17th century, when racial slavery was a punishment for servants who broke the law''. In American slavery developed nIn the 18th century due to argriculture needs of the South.