The book is an attempt to rewrite Atlantic history by reassessing the story of the slave trade. As already noted, it is based on the digital humanities project www.slavevoyages.org, which at the time of writing is fourteen years old. If we include its CD-ROM predecessor published by Cambridge University Press in 1999, the data it provides have been in the public domain for a quarter-century. In that time many millions of visitors, whether scholars, students, the media, or interested members of the public have drawn on it in ways that its compilers and editors could never have imagined. Many more again have passed through exhibitions around the Atlantic world, including the permanent display of Washington, DC’s National Museum of African American History and Culture, and the Nantes Memorial to the Abolition of Slavery that have incorporated its offerings. Few discussions of the slave trade fail to cite this resource. It is often described as a model of what the social sciences should be trying to achieve – presenting reliable, accessible, and renewable data to the interested public along with some basic interpretations. Consistent with this assessment, it has received financial support from a range of countries that almost matches the reach of the slave trade itself. In what many will see as appropriate, the only continent that has not contributed funding to its development is Africa. Public and private financial support over the years amounts to several million US dollars. Since 2018 the site has featured voyages that carried the enslaved from one part of the Americas to another. Perhaps most important, it has established separate databases on individuals who were on those voyages either as captives, or, who, like buyers and sellers of the enslaved, investors, and crew members, were responsible for the voyage itself. Moreover, it has now obtained funding to expand its coverage from destinations in the Americas to destinations in the Indian Ocean.

Yet as the preceding pages have shown, on so many major issues, general knowledge of the Atlantic slave trades is at odds with what the site’s databases demonstrate. After a quarter-century of usage and as its core databases on voyages and the people involved in them continue to grow, there is not much sign of this situation changing. This book has highlighted tensions between what the data suggests, and what is received wisdom among scholars of Atlantic history. Perhaps the most striking is that the anti-quantitative turn in the study of Atlantic slavery noted in Chapter 1 has occurred even as users draw on the site in increasing numbers. Much of the site’s traffic comes from users sampling the site to support their micro-historical studies or to note the scale of the slave trade in particular regions and time periods. While important, such usage often bypasses some major reinterpretations of the Atlantic slave trades that need to be explored.

Slavevoyages.org in fact, supports a radical revision of Atlantic history. In the current scholarship, the North Atlantic continues to appear as the center of both the transatlantic and intra-American slave trades. More precisely the North American and Northwest European role in the Black Atlantic gets by far the most scholarly attention. Yet perhaps the most important single new finding of slavevoyages is the central importance of the South Atlantic and that part of the North Atlantic trade that supplied the Spanish Americas. More transatlantic captives disembarked in South America than in the Caribbean. Within the Caribbean, Cuba, Puerto Rico, and the Spanish circum-Caribbean brought in more Africans than either Jamaica or St. Domingue. The availability since 2018 of the intra-American voyages database has further accentuated the Spanish, and beyond that, the Iberian role by providing evidence of the large flows of Africans from the British Americas to the Spanish Americas. This should surely undermine the long-held view that northwest Europeans, especially the British, were the most efficient practitioners and chief beneficiaries of Atlantic slavery. More fundamentally still, the new data displaces the old idea of the more capitalist-driven Northwest Europeans taking over a dominant role in the Atlantic from pre-capitalist Iberians at some point in the seventeenth century.

The slavevoyages data is also at odds with the current historiography in its foregrounding of the Americas rather than Europe as the organizational center of the traffic. The Americas were not only the source of a massive increase in demand for labor in the sixteenth-century Atlantic world, but the continent also had a major role in increasing supply. The reference here is not to the enslavement of Indigenous Americans – though that, too, occurred on a grand scale – but rather to the organization of transatlantic slave-trading voyages. The term “middle passage” to describe the slave trade no longer seems appropriate given that most voyages comprised just two legs, out and back, rather than three. And all this is without considering the central importance of the intra-American traffic in establishing where the displaced Africans were forced to spend the rest of their lives. Europe increasingly appears as an appendage to the system rather than its beating heart. Nevertheless, the idea that Europe was not the organizational center of the slave trade will likely be the last part of the traditional view of the slave trade to crumble in the face of slavevoyages’ data.

The Portuguese were firstcomers in the Atlantic just as the Spanish were firstcomers in the Americas. They established connections with the regions of Africa that apparently could produce the most enslaved people (West Central Africa) and conceded little to the Northwest Europeans who joined the slave trade over a century later. British dominance in the slave trade was restricted to the period 1730–1800, and even then was intermittent and never pronounced – the Portuguese carrying off 1.49 million Africans as opposed to 1.73 million on British vessels. Apart from the brief Dutch incursions into Brazil and Angola, the Northwest Europeans did not displace the Portuguese system, but rather learned to live with it. The dominant Portuguese role emerged naturally from Portuguese preeminence in the late medieval and early modern Atlantic Ocean. They took sugar cultivation out of the Mediterranean world and into first, Madeira, the Canaries, São Tomé in the Gulf of Guinea, and then to Brazil. In each case they supplied enslaved African labor, as well as the technology to turn sugar cane into raw sugar. Their maritime expertise enabled them to become the major supplier of slave labor to Spanish America.

TSTD allows us to pinpoint some of the practices that permitted the Portuguese to maintain their dominant slave-trading position in the Atlantic world. First, as we have seen, Africans spent less time on board Portuguese slave ships than did captives on Northwest European vessels. Typically, Portuguese slavers leaving Guinea/Bissau, West Central Africa, and Mozambique filled their slave decks just prior to departure before sailing to ports in the Americas that were closest to Africa. Even in the highly competitive Bight of Benin environment, Portuguese vessels were often able to fill their slave decks quickly by exchanging Brazilian gold for complete shipments of people already on board British slave ships. In the major African supply centers of West Central and Southeast Africa, which together supplied half of all captives entering the Atlantic slave trade, the Portuguese had a land-based presence, albeit tenuous, and, except for regions north of the Congo, were able to exclude all European competitors.

Perhaps even more important, the core of the Portuguese slave supply system from the interior of Africa to the sugar plantations of Brazil and eventually gold from the far interior of Brazil hinged on a set of relations with Africans and Afro-Portuguese that none of their competitors could match. Luso slave traders did not have the financial intermediaries that underpinned the British and Dutch slave trades, and did not have partnerships that like the Gregson, Aspinall, and Boats families of Liverpool trans-shipped 50,000 Africans each to the Americas. But they did have large numbers of small investors, some of whom were crew members, including even enslaved crew members, and others who had formerly been enslaved. In other words, a crew member would be assigned a part-share in an enslaved individual instead of wages. Crew also frequently shared languages with captives. A shorter time spent on board and crew with a financial interest in the enslaved and/or able to converse with captives meant that violent resistance was much less common on Portuguese vessels than on the vessels of their competitors – this even though in the eighteenth century the number of captives per crew member was much greater on Portuguese than Dutch or French slavers. Not surprisingly, there is evidence of rebellion in the Portuguese onshore holding pens rather than on Portuguese ships. The key defensive work on a British, French, or Dutch slave ship was a barricado, a strong wooden barrier built amidships that sealed off enslaved men from the rest of the vessel. A documented example on a Portuguese vessel has yet to surface.

In the Americas, the Spanish position mirrored that of the Portuguese in Africa. Outside the North American mainland (and even there not until post-1800) the Spanish retained control of the richest parts of the Americas. The value of their commodity exports from the Americas, driven by silver mining but not bullion alone, exceeded that of all their European competitors combined until the late eighteenth century. Thereafter, Spanish America continually outproduced every other American empire down to 1800, and Cuban sugar supplied half the world market by the mid nineteenth century, surpassing in value even the output of the dominant Brazilian coffee sector. By this time, of course, cotton had permitted the US to assume the mantle of the leading plantation economy in the world. Captives entering the Spanish Americas with certain exceptions were not put to work in the silver mines, but the bullion produced by Indigenous labor did facilitate the purchase of enslaved Africans in a wide spectrum of occupations in lowland Spanish America, where the largest cities in the Americas were located. Moreover, when Spanish America was heavily dependent on the intra-American traffic to replenish its labor force, Spanish merchants had a major role in this traffic. And Spanish-flagged ships were far more prominent in this business than in the transatlantic trade. In sharp contrast to the transatlantic business, almost as many Africans arrived from other ports in the Americas under the Spanish flag as under the British.Footnote ¹ It is unfortunate that the US, and the slave empires of the Northwestern Europeans still dominate the research into slavery and the slave trade in the Atlantic World.

All business activity depends on linking ultimate borrowers with ultimate lenders. The credit and insurance instruments that the Northwest Europeans developed across their respective economies, especially the British, eventually enabled them to compete with the Portuguese in long-distance trade without ever replacing them. The Portuguese had their own methods of financing and of manning slaving voyages. These methods survived the Northwestern intrusion. To put this point differently: It was economic growth that enabled British intervention in the Atlantic slave systems, rather than the slave systems that enabled British economic growth. The same was certainly true for the Dutch and the French, neither of whom showed any quickening of economic activity that can be linked to slavery and the slave trades in the Atlantic.

One of the most persistent myths in recent scholarship on the slave trade that can now be questioned is the belief in a clear causal link between slavery and the slave trade on the one hand and modern income disparities across the Atlantic world on the other. As Chapter 1 explains, slavery and slave trading were universal across the globe until very recently, at least in epochal terms.

In 1804, 45 million enslaved people lived on Earth, and all but a few million lived outside the Americas. Table C.1 shows that the African-descended share of the enslaved in the Americas comprised just 6.6 percent, or 3 million of the global total. The British held about 750,000 of these.Footnote ² People holding slaves were far more numerous in the United States and Brazil than in Britain, and absentee owners would have been as common in Portugal as in Britain. Until the St. Domingue Rebellion in 1791, in France, too, a similar pattern emerged. How very odd that such a small proportion of slaves and their owners that were British (1.7 percent of the enslaved global population, about the same proportion as the pre-1792 French, and somewhat lower than the US and Brazil ratios) should have triggered an Industrial Revolution. Why could not the larger proportions of global slaves that lived in Brazil or the Spanish Americas have triggered the first industrialization in Portugal and Spain, centuries earlier?

Adopting these larger perspectives makes it beyond credulity that slavery or the slave trade that supported it could have kick-started economic growth. It is far more likely that the key to such development lay in conditions within Britain, and eventually the Netherlands and the US, that enabled slaveholdings and other overseas activities to have had such an impact.Footnote ³ Enslaved people and their owners could not by themselves have been critically important to industrialization. As the experience of Germany, Italy, and other countries that industrialized without slavery, without Africa, and without the Americas, the evolution of the Dutch, British, and indeed all European economies could have been little different if slave colonies had never existed.

Studies of the role of the slave trade in Atlantic economic development must move beyond endless computations of how profits and trade goods in the slave trade, or any other business for that matter, enabled industrialization. Selecting any specific economic activity, for example whaling, the grain trade, the trade in hemp and iron bars from Russia, or almost any infrastructure project, including railroads – would similarly establish the indispensability of the activity to general economic growth – if subjected to an analysis that ignores the concept of value-added that is now so central to modern measurements of human welfare.Footnote ⁴

In crude terms the sum of all the value added by all activity comprises the Gross Domestic Product. Unfortunately, the practical implications of this very simple concept are ignored by most historians and all journalists. Given the interests of most historians, this matters little. But for those writing about slavery, capitalism, and we could add, the slave trade, the consequences are frequently disastrous. One result is that the new historians of capitalism, the authors of the 1619 project, most scholars of the slave trade, and all the media, frequently distort the history of slavery by greatly exaggerating its economic importance.Footnote ⁵ At the very least, given the value of colonial exports from the Americas and the fact that most enslaved people ended their lives in the Iberian world, we would not have expected industrialization to have appeared first in Britain.

The implications of the slavevoyages set of estimates of the traffic have yet to be assessed for Africa, even though those estimates have been available since 2010. Plausible estimates of the sub-Saharan African population in 1850 became available in 2014. These constitute the result of several decades of research into precolonial African demography. A comparison of the 2014 findings with slavevoyages’ estimates of those forcibly removed from the sub-continent raises questions about the size of the impact of the traffic on African populations. A review of some of the most widely read English-language Africanists indicates that some of their ideas are inconsistent with the data in TSTD. Because we have estimates of departures from Africa and data on the prices of captives on both sides of the Atlantic, we can say that the slave trade was not highly profitable compared to other long-distance trades and, moreover, accounted for a small part of the total product of all Euro-American slave-trading nations and, indeed, most African states that were involved in the business. TSTD’s estimates of the volume of the slave trade also cast doubt on the argument that external pressures from the Atlantic world transformed the nature of slavery within Africa. We know that the largest number of captives left from West Central Africa, but there is little evidence that Indigenous slavery in its vast hinterland differed in the nineteenth century from earlier forms of enslavement.

Finally, some historians interpret abolition as a way for European states to have transitioned seamlessly into a new and equally exploitative form of imperialism, especially on the African continent.Footnote ⁶ Data from slavevoyages.org on the fate of Liberated Africans after 1807 used in Chapter 7 clearly establishes the profoundly anti-Black attitudes of all the former slave powers in the Atlantic world, including the British. Nevertheless, no one should be in any doubt that in strictly economic terms the ending of 350 years of the enslavement of a cumulative total of 12.75 million people constituted a significant break with the past. The data in www.slavevoyages.org showing 1,568 British captures of slave ships beginning in 1807 are consistent with the very high costs of trying to suppress slavery and the slave trade. Such an assessment is based not just on the costs of wars of liberation, on payments of compensation to slave owners, and on dispatching fleets to attempt suppression of the slave trade. The full costs must also include the higher prices for sugar, coffee, cotton, indigo, and other plantation produce that were the results of abolition. Consumers around the world would have continued to benefit if slavery itself had continued and the Liberated Africans had remained enslaved: Labor would have been less costly, plantation profits greater, plantation produce cheaper, and the Gross National Products of Western countries higher. The continuation of slavery in the nineteenth century would have accelerated, not hindered the industrialization of the North Atlantic world.Footnote ⁷ If abolition was not a sharp break with the past, then what is?

To return to the core theme of this book, anti-Black attitudes helped ensure that Europeans would not be among the captives carried across the Atlantic on the slave decks of ships. But as Chapter 7 shows, in the aftermath of abolition of both slavery and the slave trade, these same attitudes persisted and denied Blacks equality of opportunity. In yet another counterfactual, full equality post-abolition would surely have allowed the economy to draw on the full talents of Africans and African Americans, with all the resulting social and economic benefits. And the most important of these benefits would certainly have been stronger economic growth. In strictly economic terms, then, the path taken by formerly slave-holding nations after abolition was probably, in income terms, the worst of the three options open to them. What were these options? First, the historical reality described above; second, no abolition and thus continuation of slavery and slave trading; and third, full and equal rights for all after abolition, regardless of epidermal color. To return to Chapter 1, Homo sapiens migrated from Africa and populated the world. A century and a half since the ending of slavery in the Americas is surely long enough for us to realize that we are all descended from Black people and that we all carry genes of both slave owners and slaves. But apparently not. Racial discrimination persists.

Such speculations cannot be tested with the data in slavevoyages.org, but the project has at least brought us to the point of posing them, and it is appropriate to end with a plea for its more effective use. The project is very much a community resource in the hands of all scholars and interested contributors in the field. It is hosted by a single institution which, like the home of a learned journal, is subject to periodic change. However, it is controlled by a consortium of ten institutions comprising governments and museums as well as academic institutions. The site has no named authors or editors and has received thousands of contributions from users who are not all identified. New contributions of course require vetting and frequently editing. The editorial team at slavevoyages has dedicated many unpaid hours to this task as it seeks to expand and maintain the integrity of the core databases. In short, it is a resource both supported and drawn on by the scholarly community. The site’s editors are experts in the field, but they, too, remain unnamed in citations to the data. Of course, every edit to its databases must have a verifiable source. But the broad acceptance of the project in the scholarly community suggests that the reliability of the site is widely recognized.

Apart from recognizing the horrors of the business, the team supports no single explanation or interpretation of the different Atlantic slave trades. The arguments made in the foregoing pages are my own, not the collective opinions of its professional and volunteer workers. But I am sure most would agree with me that if we ask anything of our users, it is that their own opinions about what happened be consistent with a greater share of slavevoyages’ several million datapoints than has so far been the case. As outlined in the preceding pages, not only should the scholarly focus on this topic be switched from North to the South Atlantic, but, most important, if we are to get closer to delineating the African experience, we need to pay more attention to the people who survived the ordeal, as well as those who imprisoned them. Herein lies the site’s huge potential for rewriting parts of Atlantic history.