Between roughly 1500 and 1866, an estimated twelve and a half million Africans were forcibly loaded onto European and American ships and transported across the Atlantic. Approximately two million died on the Middle Passage, chained in holds where space per person was measured in inches. The survivors, and their descendants, built much of the wealth of the early modern Atlantic economy — the sugar plantations of the Caribbean, the cotton fields of the American South, the silver mines and sugar mills of Brazil, the merchant houses of Liverpool, Nantes, and Boston. Portugal and Britain alone accounted for more than half the traffic. It was, by any measure, the largest forced migration in human history, and one of the most profitable commercial enterprises ever organized.
The trade was not a side-business of European modernity; it was load-bearing. Caribbean sugar paid for the British navy, and the triangular routes — manufactures to Africa, captives to the Americas, sugar and cotton home — kept ports like Bristol and Bordeaux solvent. Slave-traded cargoes helped develop modern marine insurance at Lloyd's, and the capital that financed early industrial machinery in Manchester and Glasgow flowed in part from plantation profits. Demand did not simply extract people from a passive continent: it transformed West Africa from within, arming coastal kingdoms like Dahomey and Asante with European muskets and pulling them into wars whose chief product was captives for sale, while the gun-slave cycle hollowed out the interior. The intellectual project of European Enlightenment — universal reason, the rights of man — was being written by people who held shares in slave ships; John Locke himself invested in the Royal African Company. Abolition, when it finally came in the nineteenth century, was the result of both a moral campaign of unprecedented scale — Quakers, freed people like Olaudah Equiano, mass petitions, the 1807 British ban and the Royal Navy's anti-slaving squadron — and a calculation by industrialists that wage labour was cheaper. The trade left, as its primary legacy, the African diaspora of the Americas — about 200 million people whose ancestors did not choose to be there, and whose presence has shaped every aspect of the New World's culture, politics, and economy, from Brazilian Catholicism to American music.
Every contemporary American conversation about race, every debate about reparations, every pattern of urban segregation, every disparity in wealth and incarceration sits on top of the demographic and legal residue of the trade. The 2019 1619 Project and the rows it provoked, the toppling of slave-trader statues in 2020, lawsuits against firms whose fortunes trace to the traffic — all are arguments over a ledger never closed. It is not a chapter that closed.