Middle Passage Death Rates Estimated at 15–25% in Early Decades

Scholarly analysis of early Atlantic slave voyages indicates that mortality during the Middle Passage in the early sixteenth century ranged from roughly 15 to 25 percent of captives per voyage, driven by dysentery, dehydration, scurvy, smallpox, and the brutal conditions of confinement. Enslaved people were chained in spaces as small as 18 inches high for voyages lasting six to fourteen weeks. Those who died were thrown overboard. These death rates declined somewhat in later centuries as traders sought to protect their 'investment,' but remained catastrophically high throughout the trade's history.