David Eltis and Martin Halbert of Emory University, in Atlanta, led a remarkable effort in which scholars from a dozen nations pooled their work to create an online database of records from almost 35,000 separate slave voyages. Its most recent iteration, released in 2009, estimates that between 1500 and 1840, the heyday of the slave trade, 11.7 million captive Africans left for the Americas—a
