A Brief Overview of the Trans-Atlantic Slave Trade

The Middle Passage

Whatever the route taken, conditions on board reflected the outsider status of those held below deck. No European, whether convict, indentured servant, or destitute free migrant, was ever subjected to the environment which greeted the typical African slave upon embarkation. The sexes were separated, kept naked, packed close together, and the men were chained for long periods. No less than 26 percent of those on board were classed as children, a ratio that no other pre-twentieth century migration could come close to matching. Except for the illegal period of the trade when conditions at times became even worse, slave traders typically packed two slaves per ton. While a few voyages sailing from Upper Guinea could make a passage to the Americas in three weeks, the average duration from all regions of Africa was just over two months. Most of the space on a slave ship was absorbed by casks of water. Crowded vessels sailing to the Caribbean from West Africa first had to sail south before turning north-west and passing through the doldrums. In the nineteenth century, improvements in sailing technology eventually cut the time in half, but mortality remained high in this period because of the illegal nature of the business. Throughout the slave trade era, filthy conditions ensured endemic gastro-intestinal diseases, and a range of epidemic pathogens that, together with periodic breakouts of violent resistance, meant that between 12 and 13 percent of those embarked did not survive the voyage. Modal mortality fell well below mean mortality as catastrophes on a relatively few voyages drove up average shipboard deaths. Crew mortality as a percentage of those going on board, matched slave mortality over the course of the voyage, but as slaves were there for a shorter period of time than the crew, mortality rates for slaves (over time) were the more severe. The eighteenth-century world was violent and life-expectancy was short everywhere given that the global mortality revolution was still over the horizon, but the human misery quotient generated by the forced movement of millions of people in slave ships cannot have been matched by any other human activity.