Origins of American slavery: Was it inevitable?

Slavery, as you say, did not start until 1697. The initial blacks in 1619 were not the slaves of the cotton and tobacco plantations we ociate with the south just prior to the Civil War. Slaves were used because it would have been impossible to make a profit if field hands had to be paid. There was a triangular trade system set up whereby rum and sugar cane from the Caribbean was sent to the colonies, and rum from those raw material was produced and sent to England. It was during this trade that demand for cotton and tobacco out stripped the call for rum. Then the Caribbean nations began sending slaves to the US southern states as field hands. Once the slave traders saw this they began sending slaves directly to North America rather than the Caribbean.