The Slave Coast was the main slave trading area in Africa, located in West Africa between the Senegal River and the Congo River. Each of the major slave trading nations would keep 'factories' where captured slaves were kept prisoner until a ship could come to take them across the ocean. Slaves would be purchased from African slave-traders or captured there and then packed on boats for the voyage to other parts of the world.
Conditions on the passage to America were terrible. Sometimes half the cargo would die from starvation, dehydration, or simply from suicide. At times the slave merchants would throw sick slaves overboard, because their insurance would pay for slaves lost at sea, but if brought to land alive they would be sold for less than the cost of carrying them. In one famous case a British court agreed that this was a perfectly legal and acceptable practice.
Enslaving Indians was also common, but the practice was declining in the Americas by the time of the Revolution. Indian slaves could escape and return to their people, but Africans could hardly swim home across the ocean. Without somewhere to escape, they had little choice but to remain in slavery. In addition, many slave owners considered African slaves to be better workers than Indians.
Upon arrival in America, sick slaves would be sold first. Most people who bought these 'junk slaves' received them at a reduced rate and tried to nurse them back to health. If they succeeded they could sell them at a large profit. Certain slave traders in the south specialized in this sort of 'recycling'.
Sometimes slaves would be sold at a negotiated price, often through newspaper ads. On other occasions, the slaves would be inspected and put up for auction with the highest bidder receiving the slave.
Once the slaves were purchased they were the absolute property of the slave owner. They were assigned to any work their owner decided upon. Many worked at hard field labour while others worked as domestic servants or were trained in skilled professions. Sometimes masters with skilled slaves would rent out their slaves to others and keep the wages for themselves.
Slaves had no right to education, health care, or religious instruction. They could be beaten any way their master saw fit. It was common for them to be whipped until their skin was raw and have salt rubbed into their wounds. Some developed other methods of torture, and a few thought that slaves could be made more docile and co-operative by treating them gently. Slaves had no right to traditional family ties, as their spouses and kin could be sold to another owner at any time.
Near the beginning of the American Revolution, slave labour had become central to the economy in many places. Most whites in the southern colonies owned slaves for their cheap labour, and the large plantations we know from Civil War era