Slave Voyages: not only Trans-Atlantic but also Intra-American!

This blogpost is mainly intended to announce a major overhaul for one of the most important sections on my blog:

The page referred to above is now featuring new screenshots taken from the invaluable Trans-Atlantic Slave Trade Database as well as the additional Intra-American Slave Trade Database. Reflecting the current state of knowledge. I am convinced that the data contained on that page can be very educational and useful for anyone wanting to learn more about their African roots. Just as long as you keep in mind inherent limitations and inform yourself about the relevant context. This kind of aggregated information is probably most useful on a population level.1 But also for your personal quest it can provide you with a very valuable starting point! In particular in order to judge the historical plausibility of any DNA test results you may have received. Not only regional admixture or haplogroups but also African DNA matches. And even DNA matches from across the Afro-Diaspora!2

***(click to enlarge)

Despite its limitations the Trans-Atlantic Slave Trade Database (TAST) is simply the most comprehensive and up-to-date resource available when wanting to look into Trans-Atlantic Slave Trade patterns. The website was updated in 2019. It now includes information about more than 36,000 Trans-Atlantic slave voyages! See also this recommendation by Henry Louis Gates.


““If there were a Pulitzer Prize given for historical databases, the Transatlantic Slave Trade Database would win it, hands down,” says Gates, Alphonse Fletcher University Professor at Harvard.” (source)


I myself have often relied heavily on the Trans-Atlantic Slave Trade Database as some sort of baseline. To establish historical plausibility within my ongoing research efforts on how personal DNA test results of Afro-Diasporans may already be in alignment with historical expectations. See also:

It can be very tempting to correlate slave trade records with population genetics or assumed ethnic/regional origins of Afro-descended populations. Given the absence of more straightforward information. But such an approach can hold many pitfalls. Even if the Slave Voyages database is deemed to provide nearly fully coverage for any particular country. This is because you cannot just simply assume that there will be a direct extrapolation from the data at hand. Reality is too complex regrettably. Several factors need to be taken into account. Mainly to do with incomplete knowledge about the demographic evolution of enslaved Africans and their descendants. See the updated section for more detailed discussion. This aspect might be most pertinent:


  • Intra-American Slave Trade, Domestic overland Slave Trade and Post Slavery migrations have resulted in great deal of additional intermingling and diversification of African lineage. This is especially true for the USA and Brazil because of their continental size. But in fact also for most parts of the Caribbean and Latin America.


Table 1 (click to enlarge)

Based on these estimates (taken from O’Malley, 2009),  Intra-American Slave Trade for North America was around 15%. The actual shares per state do show important variation. For Virginia and South Carolina this share of slave trade by way of the Caribbean is  quite minor: around 10%. However for other states it is more substantial. Do keep in mind though that Domestic (overland) Slave Trade is not taken into account. While actually going by sheer numbers this type of Slave Trade was most significant for the USA. An estimated 1 million enslaved African Americans (often with Virginia background) are known to have been victimized by the so-called Second Middle Passage (see this link).


Obviously there will be other factors as well that could explain genetic results being disproportionate to what you might expect based on slave trade data. Substructure within any given Afro-descended population also being highly relevant. This is something which I have blogged about several times already and also in upcoming blog posts I will return to this important topic. Within the remaining part of this current blog post I will discuss the following:

  1. Trans-Atlantic Slave Trade Database
    • Newly added Portuguese & Spanish Slave Voyages (1500’s) corroborate Upper Guinean founding effect for many Hispanic Americans
  2. Intra-American Slave Trade Database
    • Disclaimers
    • Intra-American Slave Trade Patterns for the USA
  3. Final Passages: The Intercolonial Slave Trade of British America, 1619-1807 (G. E. O’Malley, 2014)


1) Trans-Atlantic Slave Trade Database 


“The 2019 version of the transatlantic slave trade database contains 36,108 voyages compared to 34,940 in 2008 (and 27,233 in the 1999 version of the database that appeared on CD-ROM)” (source)

“the world cannot be understood without numbers, and it also cannot be understood with numbers alone.” (source)


I have always been convinced of the tremendous informational potential to be uncovered from slave trade statistics as well as other overviews listing ethnic/regional origins of Africans in the Americas.3 In particular in regards to answering urgent questions about the specific African lineage of Afro-descendants. This African lineage will in fact practically always be a composite for Trans-Atlantic Afro-Diasporans. Including ancestry from multiple places and many distinctive populations! Still great insights about the approximate proportions of one’s diverse African ancestry can be obtained. Also the most likely primary component of one’s multi-faceted African lineage can be hinted at in many cases. Naturally to be combined with any other ancestral clues you can obtain from DNA testing (regional admixture, DNA matches, haplogroups etc.), genealogy, local history of your earliest known ancestral places within the Americas, African cultural retention for those places etc..

Despite its limitations the Trans-Atlantic Slave Voyages Database is simply the most comprehensive and up-to-date resource available when wanting to look into Trans-Atlantic Slave Trade patterns. Numerous historians have contributed to this database and it has practically become a standard reference among researchers. Nevertheless careful interpretation is always a must. I mention several disclaimers & pitfalls on the page below. Also listed are 2 very useful links discussing the database and its latest update in 2019.

The Slave Voyages website has been in existence already since 2008! While the underlying database was originally created on CD-ROM in 1999! I myself have been aware of it since atleast 2010 when I first created screenshots which were previously featured on my blog. Because of several updates in the meanwhile I have decided to do a thorough revision. Really you will need to go through the main page itself for all the many insights to be gained. However right now I will just focus on one particular highlight which is close to heart (being Cape Verdean descended myself). It involves the Upper Guinean Founding Effect for Hispanic Americans. A phenomenon I have been blogging about since the start of this blog in 2014!


Upper Guinean Founding Effect for Hispanic Americans

Table 1.1 (click to enlarge)

Many insightful patterns on display in this overview. Just to highlight a single one: notice the remarkably high level of Senegambian slave trade for the Hispanic Caribbean (minus Cuba) as well as for the so-called Circum-Caribbean (=mainly Mexico & Colombia). A clear indicator of the Upper Guinean Founding effect I have blogged about since 2014 already.  Source: Trans-Atlantic Slave Trade Database (2020) (


Table 1.2 (click to enlarge)

Enslaved Africans departing from Cape Verde were destined overwhelmingly to the Spanish Americas. In fact the 13,4% share for the Caribbean is mainly covering the Hispanic Caribbean (see this overview)! Take note as well that “offshore Atlantic” is referring to Cape Verde!  Source: Trans-Atlantic Slave Trade Database (2020) (


Table 1.3 (click to enlarge)

Cape Verde was the first main Trans-Atlantic slaving entrepot in the 1500’s.  However after a steep decline of slave trading activities in the 1600’s/1700’s Cape Verde was dragged back into the “odious commerce” again in the early 1800’s, see also this link. Source: Trans-Atlantic Slave Trade Database (2020) (


Coverage of slave trade data from Cape Verde has increased tremendously! It seems this update took place already in 2016. Compared with the 2010 version of the Trans-Atlantic Slave Trade database a tripling in number of disembarked captives has occurred (35,669 versus 108,700; see this previous screenshot taken in 2014 and this one from 2020). Although curiously it seems the separate Estimates section has not yet been adjusted.4 Either way a great improvement has been achieved by the addition of a large number of early Portuguese & Spanish Trans-Atlantic slave voyages destined for the Hispanic Americas. Usually departing from either Upper Guinea (incl. Cape Verde) or Angola but also from São Tomé & Principe.

These early slave voyages (1500’s) were mostly missing in the previous editions of the Trans-Atlantic Slave Trade database (before 2016) causing distortion of the main regional origins of Hispanic Americans when going by documented slave trade (esp. for Dominicans and Puerto Ricans). This has now however been corrected. Other slave voyages from later time periods have been added as well. All contributing to a much greater coverage of African slave trade for the Hispanic Americas as a whole.

I have described the possible implications of these tables in much greater detail elsewhere (incl. on the main page). But in short: it can be established from the overviews above that overwhelmingly (~75%) slave trade departing from Cape Verde took place in the 1500’s and was mostly directed to the Spanish ruled colonies of Latin America (incl. Hispanic Caribbean around 90%). And in fact many Dominicans (=Hispaniola), Puerto Ricans,  Mexicans & Meso Americans and Caribbean Colombians (=Circum-Caribbean) are likely to trace back a greater part of their African lineage to this earliest period of Trans-Atlantic Slave Trade: 1500’s -1600’s (see this overview).

Although because of additional (Intra-American) Slave Trade in the 1700’s/1800’s actually there might still be some considerable substructure for many Hispanic Americans. Correlating with either geography and/or degree of admixture/mestizaje. The exact degree is perhaps yet to be determined but either way this addition of new slave voyages has been very beneficial for showcasing the early Upper Guinean founding effect for many Hispanic Americans.5 Something which I have been blogging about since starting this blog in 2014. For more details:


2) Intra-American Slave Trade Database

Despite its limitations the Intra-American Slave Trade Database is simply the most comprehensive and up-to-date resource available when wanting to look into Intra-American Slave Trade patterns. The database was integrated within the website in 2019. It now includes information about more than 10,000 Intra-American slave voyages! See also this announcement.



the dominant pattern to emerge from this new intra-American database is the importance of the Spanish Americas as, probably, the second largest broad region of slave disembarkation in the Americas. Looking at the transatlantic traffic alone vastly understates the importance of Spanish territories to the history of slavery in the Americas, but the data contained here adds thousands of slave voyages from (mainly) Portuguese, British, and Dutch colonies to Spanish dominions, mostly in Cuba, Puerto Rico, Mexico, Colombia, Venezuela, and the Río de la Plata region. For those interested in the slave trade to the many Spanish colonies across the New World, it is imperative to use both the transatlantic and the intra-American databases, in order to examine the volume and routes of this traffic as well as the origins of African and African-descended captives.” (source)


One major shortcoming of the Slave Voyages website used to be that only Trans-Atlantic Slave Voyages were included. While Inter-Colonial Slave Trade between for example the West Indies and North America was not in scope. However in 2019 the website expanded with a new section featuring exactly these Inter-Colonial or rather Intra-American Slave Voyages.  A very useful addition, although naturally still a work in progress! On the main page I have posted a few insightful overview tables which I have myself generated from the database (in October 2020). I am hopeful that this section will soon have new updates and greater coverage. As well as preferably a separate Estimates page, similar to the Trans-Atlantic Slave Voyages Database.

To be more precise this Intra-American Slave Voyages database only includes slave voyages which did not depart directly from Africa but rather from a slaveport already located within the Americas. The captives would still usually be African-born.6 However they would have been on transit after their first Middle Passage. Often leaving again within a few weeks or months. So no actual seasoning took place in most cases. Destinations often being marginalized colonies within the British Empire without any major Trans-Atlantic Slave Trade. Or else the French Caribbean and even more so the Spanish Americas. Because of the 1494 Treaty of Tordesillas Spain was afterall dependent on other European nations for its slave trade. Initially under Asiento but right from the start also a large scale clandestine slave trade developed. Often performed by European slave traders located in the West Indies, but actually also from Brazil.

For more background details read the following articles, incl. a very insightful essay cowritten by the main creators of this database.


(Not meant to be exhaustive and in addition to what has been listed in section 1 of the main page)

  • Although of crucial importance and astounding numbers involved Intra-American Slave Trade was still minor compared to overall Trans-Atlantic Slave trade. According to estimates for the USA it could be around 15% of total slave trade (see table 1). While for the Spanish Americas an estimate of 30% has been made (see this essay). There might be significant variation though when zooming into specific areas, subregions etc..
  • Obviously undocumented slave voyages (usually contraband) are NOT included within this database. Unless these voyages were intercepted or written about otherwise. This will be particularly relevant for both the French and also Spanish ruled colonies across the Americas.
  • Coverage of Intra-American Slave trade carried out by the British and the Dutch is apparently quite good according to the website itself. Although still spotty for the earliest period. Brazilian Intra-American Slave Trade to Rio de la Plata is also impressively included. However “Intra-American traffic to the French Caribbean is vastly underrepresented in this database“. I imagine that also Intra-American Slave Trade carried out by the Spanish themselves is still greatly missing in the database. Especially in between the Hispanic Caribbean and the mainland. And in particular for the earliest period in the 1500’s when Cartagena and Veracruz were not yet designated as official slave ports.
  • Domestic overland Slave Trade and Post Slavery migrations have resulted in great deal of additional intermingling and diversification of African lineage. On top of what was already the result from both Trans-Atlantic and Intra-American Slave Trade combined. This is especially true for the USA and Brazil because of their continental size. But in fact also for most parts of the Caribbean and Latin America.

Intra-American Slave Trade Patterns for the USA 

Table 2.1 (click to enlarge)

Follow this link for underlying numbers. Source: Intra-American Slave Trade Database (2020) (


Just to reiterate according to estimates Intra-American Slave Trade by way of the West Indies covers about 15% of total slave trade (internationally and by sea) for the USA. For Virginia and South Carolina it was even less: around 10%. Therefore Trans Atlantic Slave trade is far more important for the USA, generally speaking. Then again for certain states this Intra-American Slave Trade was more significant than for others. And also the timing of this Intra-American Slave Trade may have resulted in disproportionate founding effects. Domestic Slave Trade however involved a greater number of people (possibly 1.2 million) than Trans-Atlantic and Intra-American Slave Trade combined (around 450,000 disembarked).

Keeping in mind the relative significance of Intra-American Slave trade very useful information can still be obtained. In particular when combined with other leads. In table 2.1 above either Barbados or Jamaica are being shown as most important supplier of enslaved Africans. For Virginia and South Carolina it is Barbados (usually also taking place in earlier time periods). However for New York, Georgia and Louisiana (=Gulf Coast) instead it is Jamaica.

Also interesting to take note of the considerable share of the Dutch Caribbean for New York (15%). Apparently this slave trade continued even after the formerly Dutch colony of New Amsterdam came under British control in 1664. The last documented slave voyage (111935) departing from Curacao arrived in New York as late as 1766! See also:

Also a distinctive share of Martinique (6.4%) and St. Domingue/Haiti (6.3%) being mentioned for Louisiana. Aside from also minor slave trade by way of the Danish West Indies for a few states otherwise it is other British ruled Caribbean islands through which Intra-American Slave Trade was being routed.


3) Final Passages: The Intercolonial Slave Trade of British America, 1619-1807

This is an award-winning book written by one of the main creators of the Intra-American Slave Trade Database: Gregory E. O’Malley. It is based on exhaustive and excellent research. Highly recommended reading for anyone who is wanting to learn more about this topic:

I have myself learnt a great deal from this truly priceless book! And I aim to integrate some of its key insights within my upcoming research findings. For now I will suffice with listing a few notable quotes as food for thought so to speak. Also for purely educational purposes I will include a few illustrative overview tables from the book.7



USA related


Scholars of the antebellum period emphasize the overland trade’s importance for slavery’s expansion, since legal transatlantic importations ceased after 1807, but the antebellum domestic slave trade had an important precursor in the colonial and early national periods, though it was smaller in scale. Enslaved migration to the North American interior can be conceived of in two phases—first, a dispersal of Africans from Atlantic entrepôts between the mid-eighteenth and early nineteenth centuries, and second, the forced migration of American- born slaves from older plantation areas to the burgeoning southwest cotton fields, starting in the late eighteenth century and reaching unprecedented levels in the antebellum period.” (O’Malley, 2014, p.265)


People who departed Africa from the Bights of Benin and Biafra each accounted for between one-quarter and one-third of the forced migration to Barbados and Jamaica, with captives from Senegambia, the Gold Coast, and west central Africa also composing smaller but significant portions of the population (see Table 6). Presumably, people from all of these regions entered the intercolonial slave trade, but the decisions traders made suggest that these people were not all equally likely to face transshipment. If traders like Stede and Gascoigne were typical in transshipping captives from the Bight of Biafra away from the principal American markets, Igbos were probably overrepresented in colonies that relied on intercolonial shipments of slaves.” (O’Malley, 2014, p.134)


As such, Igbo people from the Bight of Biafra might have faced a particular likelihood of transshipment (or overland march) from an entrepôt of the slave trade—such as Charleston, the James River, or Bridgetown—to one of the marginal slaveholding colonies of the mainland, such as North Carolina or Georgia. This bias toward Igbos might have been most pronounced in the earliest decades of North Carolina slavery, when Virginia was an especially important source of captives. People from the Bight of Biafra accounted for nearly half of the Africans shipped directly from Africa to Virginia between 1660 and 1730; surely, they accounted for a major portion of the North Carolina trade.” (O’Malley, 2014, p.200)


Governor James Glen [of South Carolina] noted in 1754 that intercolonial merchants seized the moment. “As Negroes are sold at higher Prices here than in any part of the King’s Dominions,” he reported, “we have them sent from Barbadoes, the Leeward Islands, Jamaica, Virginia and New York.” (O’Malley, 2014, p.178)


Between 1710 and 1724, when direct deliveries of enslaved people from Africa to South Carolina emerged, an inordinate number of them (nearly 60 percent) came from Senegambia. Another third of the direct arrivals came from the Gold Coast, and perhaps one in ten hailed from the Bight of Biafra. Complicating this fairly simple tripartite picture of transatlantic arrivals, however, was intercolonial trade from the Caribbean, which continued to supply about half of South Carolina’s enslaved immigrants in this formative period. The ethno-linguistic composition of the intercolonial migration differed markedly.” (O’Malley, 2014, p.185)


Although Senegambian people predominated in direct African trade to South Carolina, they composed only a small share of the forced migration from Africa to the British Caribbean in these years. Traders headed to the islands tended to acquire captives in African regions where larger cargoes of people could be assembled. Akan- speakers from the Gold Coast accounted for half of the captives disembarking in the British Caribbean, and another quarter of arrivals comprised people from the Bight of Benin (Figure 5). Peoples from a smattering of other African regions made up the remainder of the Caribbean migration. Assuming that the intercolonial trade from the British Caribbean to South Carolina reflected the ethnic composition of the transatlantic migration to the British Caribbean, this intercolonial trade must have diversified the enslaved population in South Carolina considerably.” (O’Malley, 2014, p.185)


An array of African peoples populated the traffic, and although plantation owners had preferences for their captives’ backgrounds, they could not count on having those preferences met. Even a prominent merchant like Laurens, in the biggest slave market in British North America, saw that he might have to settle for third, fourth, or fifth choices. In fact, despite his emphatic rejection of “Callabars” (captives from the Bight if Biafra) as unsuitable for the South Carolina market, Laurens repeatedly managed to sell people of just that description to labor-hungry planters.” (O’Malley, 2014, p.342)



French Caribbean / Louisiana related


As such, the clandestine trade between British and French islands in the eighteenth century likely increased the proportion of Akan and Igbo men and women reaching French territories far beyond what the direct African trade might suggest.” (O’Malley, 2014, p.254)


African traders from Liverpool alone claimed to deliver more than 12,000 people to Guadeloupe between the British conquest in 1759 and the end of the war in 1763. Likewise, the British occupied Havana for less than a year, 1762–1763, but in that time, British traders sold somewhere between 3,000 and 10,000 enslaved Africans to Cuban colonists“. (O’Malley, 2014, p.302)


Thus, intercolonial trade continued to bring significant numbers of Igbo and Akan people to the French Caribbean, to settle among the west central Africans who predominated among the direct African arrivals (Figure 10). This influx of Igbo and Akan captives marked an especially significant shift in the migration to Saint- Domingue and Louisiana because those colonies (unlike Martinique and Guadeloupe) had rarely relied on British slave traders in earlier decades“. (O’Malley, 2014, p.313)


By the end of the 1780s, Louisiana imported more than one thousand Africans from the Caribbean annually, with Jamaica the most important source and hundreds of Africans also arriving from Dominica, Montserrat, Cuba, and Saint-Domingue. In the 1790s, Caribbean transshipments to Louisiana slowed, owing largely to new restrictions from anxious Spanish authorities in the wake of the Saint- Domingue rebellion. In 1796, Louisiana prohibited slave importations altogether. For the enslaved population in Louisiana, there were profound implications in the shift to relying on British colonies for most shipments of enslaved immigrants.” (O’Malley, 2014, p.310)


“Under French rule, the colony had been unique in relying on one African region, Senegambia, for the vast majority of its slave trade. But that region accounted for less than 2 percent of the African immigration to Jamaica in the late eighteenth century. The Bight of Biafra and the Gold Coast together contributed two-thirds of the people forced to Jamaica between 1771 and 1800; the Igbo and Akan peoples from these regions surely began to appear in Louisiana in significant numbers, diversifying the enslaved community.” (O’Malley, 2014, p.310)


” Southern Saint-Domingue—which often complained of the same neglect from French traders that plagued Martinique and Guadeloupe—also opened to foreign slave traders in 1783, though the opening was only temporary, whereas for Martinique and Guadeloupe, it proved lasting. After a century of futility in trying to halt such trade, French officials decided to prioritize a supply of coercible labor over enforcing mercantilist laws. Transshipment from Dominica thrived under the favorable British and French policies. Northern Saint- Domingue monopolized the attention of French traders, and the rest of French Caribbean relied heavily upon British transshipment”. (O’Malley, 2014, p.312)




Caribbean  (Windward islands) related


As Britain’s empire in the Caribbean expanded in various wars, merchants in the intercolonial trade rushed enslaved people to newly acquired territories. One such opportunity emerged after the Seven Years’ War, when the Treaty of Paris (1763) handed Britain the so-called Ceded Islands—Grenada, Dominica, Saint Vincent, and Tobago. In the first few years that these islands were in British hands, intercolonial slave traders sent numerous shipments from the older colonies, especially Barbados, carrying several thousand slaves. These deliveries focused primarily on Saint Vincent and Tobago, the last islands to be targeted by transatlantic traders directly from Africa. After the first several years of British occupation, however, transatlantic deliveries to the Ceded Islands accelerated, and this intercolonial trade quickly declined. Intercolonial merchants engaged heavily at the moment when British settlers flocked to the new territories but before transatlantic traders flooded them with enslaved Africans.” (O’Malley, 2014, p.320)



Guyana related


” Partial export records do survive from Barbados for 1772 to 1774, and these show the emergence of other important markets for Barbados transshipments, with several hundred Africans sent to Dutch Demerara.” (O’Malley, 2014, p.369)


The trade from Barbados to Demerara in the 1790s offers another example of the advantage that intercolonial traders enjoyed over their transatlantic counterparts. In 1796, during the warfare associated with the French Revolution, the British wrested control of Demerara, Berbice, and Essequibo—colonies on the northern coast of South America, now Guyana—from the Dutch. British settlers quickly expanded sugar, coffee, and cotton cultivation in these territories, and as the plantation economies grew, demand for enslaved labor surged, as well. Demerara had imported Africans throughout the Dutch era, but the shift to British control saw the slave trade to Demerara increase dramatically, peaking in 1801 with more than 14,000 Africans reportedly arriving.” (O’Malley, 2014, p.320)


The transshipment trade to Demerara in these transitional years reveals local traders’ responsiveness to changing market conditions. After the transfer of power, transshipments of Africans to the colony spiked in the first full year of British control, only to decline rapidly thereafter, as a steady stream of transatlantic shipments caught up with demand. The ventures of the vessel Demerara Packet […] —owned by Barbados merchants—made regular shipments to Demerara from its home colony.” (O’Malley, 2014, p.320)





Hispanic Americas related


Although health and gender were criteria considered in the sorting of captives at Jamaica, company records show less attention paid to ethnicity or African regional background in decisions about dispersal. As such, the British asiento surely added to the diversity of Spanish America’s enslaved populations because the forced migration to the British Caribbean drew from a wide array of African regions in the period.” (O’Malley, 2014, p.238)


Spanish slaveholders, like many throughout the Americas, were less fond of exploiting Igbos than some other enslaved African groups, so there is some reason to expect that the South Sea Company avoided them, especially since Spanish buyers often paid in silver, giving them more influence with traders. Nonetheless, to most purchasers, the most important criteria was health, so Igbos who survived the Atlantic crossing to Jamaica in decent condition faced some likelihood of transshipment to Spanish America.” (O’Malley, 2014, p.238)


Starting in 1766, Barbados found a new outlet for the export slave trade. The Spanish crown granted a new slave trade monopoly to a Spanish company that centered its importations in Puerto Rico. From there, the company distributed African people to the other Spanish territories. Import records from Puerto Rico show that Barbados served as the company’s major source for human commodities. Thousands of Africans annually faced transshipment from Barbados to Puerto Rico between 1766 and 1772, mainly in Spanish vessels.” (O’Malley, 2014, p.369)



Diversification of African lineage vs Clustering of African Identities

Also read: Ethnic identities of African-born slaves: valid or imposed? (2015)


By shuttling people between American colonies, the intercolonial slave trade added a degree of complexity to the dispersal of people and cultures to various American communities” (O’Malley, 2014, p.342)


“An astonishing array of people crossed the Atlantic from Africa. Even though many traversed the ocean on ships with people of a similar background, the intercolonial trade increased the mixing of peoples from various African regions. As the routes of the slave trade—transatlantic and intercolonial—overlapped and meandered through time, they scattered and blended African peoples from a smattering of different regions across the American landscape in myriad combinations.” (O’Malley, 2014, p.344)


Spoken nowhere in Africa, Gullah nonetheless injected America with African culture and offered enslaved people a social and cultural sphere that colonists of European descent could not readily penetrate. Gullah thus offers one example of how diverse African settlers both adapted to one another and their new surroundings while transplanting vital elements of African culture and seeing them flower in new hybrid forms.” (O’Malley, 2014, p.346)


“This diversity limited opportunities for preserving any one African culture intact in an American colony, but the creation of new hybrid languages, rituals, and musical styles attests to the flowering of new African American cultures and to the resilience of the human spirit” (O’Malley, 2014, p.347)




The tables shown below are based on ground breaking research! Highly educational to gain greater understanding of the entangled beginnings of African Americans as an ethnic group within its own right. I will not comment that much for now. As I intend to refer to this data in upcoming blog posts. Take note however from the first overview how early Intra-American Slave Trade by way of either Jamaica or Barbados is likely to have brought in mostly enslaved Africans from the Bight of Biafra (31%), Bight of Benin (26%) and the Gold Coast (17%), in other words the wider Lower Guinea area.

Furthermore notice from Table 3.3 that in 1700 the Chesapeake easily had the largest enslaved population in North America. Founding generations arriving by way of both Trans-Atlantic and Intra-American slave trade. The latter flow of people representing a minor estimated share of 14% by 1710 (see table 3.4). However because of the early onset of local population growth quite rapidly a majority of enslaved people living in Virginia/Maryland would actually be American-born. In other words constituting the first generations of locally born African Americans! See also:

Virginia would continue to have the most numerous African American population well into the mid-1800’s (see this link). Due to subsequent Domestic Slave which is known to have affected Virginia more than any other state this lead to a great dispersal of Virginia-born African Americans. The African lineage of their descendants who are now spread all over the USA therefore might still often reflect the specific slave trade patterns of that state. In particular increased Bight of Biafra ancestry. See also:

When looking into the data for South Carolina (table 3.7) it is noteworthy firstmost how up till 1720 Intra-American Slave Trade was very substantial for South Carolina. As Trans-Atlantic Slave Trade was relatively late to start (and also finish) for South Carolina when compared with Virginia. See also this overview taken from the Trans-Atlantic Slave Trade database:

For North Carolina (see table 3.8) however it seems that neither Trans-Atlantic nor Intra-American Slave trade was decisive for local population growth. Instead Domestic Slave Trade was most important for populating North Carolina in the 1700’s. Naturally the same thing would happen also in the 1800’s for most other states in the Deep South. See also:



Table 3.1 (click to enlarge)


Table 3.2 (click to enlarge)



Table 3.3 (click to enlarge)


Table 3.4 (click to enlarge)



Table 3.5 (click to enlarge)


Table 3.6 (click to enlarge)


Table 3.7 (click to enlarge)


Table 3.8 (click to enlarge)





1) The very low odds of tracing back to Africa for African Americans were highlighted in 2017 during an episode of Finding Your Roots by Henry Louis Gates Jr.. The guest of his show, musician and producer Questlove, was found to be descended from one of the last enslaved Africans to arrive in the US on a slave ship. The infamous Clotilda. This slave voyage can be found in the Trans-Atlantic Slave Trade Database with voyageID 36990.


“The discovery of ancestors on the Clotilda isn’t just an interesting genealogical fact. As Gates says, it means that Questlove is the only African-American he knows who can answer a question that many have asked: not only where in Africa his ancestors came from, but how exactly they got to the U.S. in the first place.” (Time, 2017)


2) Afro-descendants from different parts of the Afro-Diaspora may be related in several ways. Firstly of course by way of shared African ancestors. One of O’Malley’s (2014, pp. 21-25) key findings was that:


one thing the vast majority of captives in the British intercolonial trade shared was that they were Africans who had recently arrived in the Americas. Of the 26,830 people whose background is noted in the intercolonial database, 24,713 of them (more than 92 percent) were described as “New Negroes,” “Africans,” or a more specific African ethnicity. Fewer than 8 percent of people were described as “Seasoned” or as otherwise having spent substantial time in the Americas.


Which goes against the still widely held belief that people being transported from the West Indies to North America would have been locally-born or atleast resident for a longer period already. Instead it now appears that these captives would overwhelmingly have been African-born and merely on transit in the West Indies.

Perhaps redundant but it might still be worth reminding that the MRCA‘s (most recent common ancestors) shared between yourself and your matches will not per se have been of the same background as your matches themselves. Especially due to ongoing migrations there are usually several possible ancestral scenario’s to consider whenever you get “matched” with someone. Assumptions about the direction of gene flow may be proven wrong after follow-up research. Context is everything and historical plausibility combined with solid genealogical research should be leading instead of wishful thinking or unfounded conjecture.

Generally speaking I suppose several ancestral scenario’s may be valid when looking into Caribbean matches for African Americans:

  • Shared African Lineage, whereby one African ancestor had two close relatives/children; one ending up in the Caribbean and the other one in North America
  • Shared European lineage, whereby one European ancestor left offspring in both the Caribbean and in North America
  • Shared Caribbean lineage to be traced back to Intra-American slave trade involving Caribbean-born captives
  • Shared Caribbean lineage to be traced back to voluntary migrations from the late 1800’s/ early 1900’s onwards
  • Shared African American lineage to be traced back to African Americans migrating to or passing through the Caribbean (both during Slavery and afterwards) and leaving offspring there. Especially relevant for the Bahamas, Trinidad, Haiti and the Dominican Republic.

3) It goes without saying that one must never forget that actual people are hiding behind these statistics. As well as all the horrors and dehumanizing experiences they went through! In order to obtain greater understanding it is indispensable to learn as much as possible about the wider historical context. The Intra-American Slave Trade and its profit-driven serial displacement of people across various colonies epitomizes the commodification of human beings! Reaffirming the lost identities of African ancestors has become very complex in the process but is not impossible! Tracing African Roots inspite of diversification of African lineage still holds immense rewards!

The separate African Names Database is also a great resource featured on the same website. Follow this link for it:

4) For Puerto Rico for example the updated database now gives 5,698 Senegambians who disembarked out of a total of 25,557. Therefore a proportion of 22%. Which is plausible also given several studies which have highlighted how Upper Guinean DNA makes for a significant component within the African genetic heritage of Puerto Ricans (see this link for an overview). The estimates for Puerto Rican Trans-Atlantic slave trade seem to have been unchanged however. The Estimates page still gives an unrealistically low number of Senegambian captives. Something which I remarked upon already in 2014 actually. Out of a total of 26,881 disembarked captives in Puerto Rico only 355 are estimated to be Senegambian. A share of merely 1.3%. These estimates are clearly in contradiction of the documented records which are now available in the database! Hopefully this will soon be corrected by the website.

Comparison of estimated slave trade for Puerto Rico vs databased slave trade

(click to enlarge)


5) An overly USA-centric perspective may have prevented a full realization of how significant Upper Guinean ancestry seems to be for Hispanic Americans. Especially in comparison with African Americans. The inclusion of these early Iberian (Portuguese/Spanish) Slave Voyages into the database will be incredibly useful therefore for greater understanding. However it should be pointed out that Latin American, Iberian and Cape Verdean historians (such as António Carreira) have always been aware of the significance of this early slave trade by way of Cape Verde. Their research findings may not have been so widely known in the USA merely because their work has mostly not been published in English.

Either way in 2016 I myself already blogged the following:


The exact degree of Senegambian origins and any possible reasons for its relative greater dilution among African Americans are yet to be determined. But at any rate the often made assertion that African Americans would have the greatest proportional share of Upper Guinean ancestry within the Americas may no longer be tenable. It might very well have to be rephrased into African Americans have a greater share of Senegambian ancestry only when compared to the English speaking West Indies and Haiti but not so when compared with the Hispanic Caribbean and Mexico/Central America. The persistent Upper Guinean genetic imprint among many Hispanics […] can no longer be ignored


Overview below is featuring my final research findings based on AncestryDNA results (2013-2018 version). It can be established that the predictive accuracy of  “Senegal” was not 100% accurate but still quite solid. And it was being reinforced by a somewhat weaker defined “Mali” to describe a genetic Upper Guinean component. It can be seen that “Senegal” + “Mali” is clearly culminating for Senegambians, Guineans, Malians and Cape Verdeans, as it should! But also otherwise the ranking is in line with expectations. At least when going by the latest insights and not relying on a USA-centric perspective. In regards to the (Trans-Atlantic) Afro-Diaspora we can observe how “Senegal” + “Mali” is most prevalent among Mexicans, Puerto Ricans and Dominicans. Seemingly reflecting a major Upper Guinean founding effect among Hispanic Americans. I have blogged about this topic many times already (starting in 2014). And I intend to do so again eventually as my updated 23andme surveyfindings are also in support of this remarkable phenomenon!

*** (click to enlarge)

Stats Upper Guinea (diasp)

This table features an approximation of an Upper Guinean component by combining “Senegal” and “Mali” group averages. The ranking among Afro-Diasporans is more or less in line with historical sources. Illustrating how a Upper Guinean founding effect among Hispanic Americans may have been very significant!


6) Aside from African-born captives actually also Native American captives used to be numerous especially during the start of Intra-American Slave Trade. Involving Native Americans being enslaved from all over the Caribbean (both mainland and islands). And usually also put to work somewhere on the Greater Antilles: either Cuba, Hispaniola or Puerto Rico. The enslavement of tens of thousands if not hundreds of thousands of Amerindians from all around the Caribbean Basin (as far north as South Carolina and as far south as the Amazon river in Brazil, but also places like Yucatan, Honduras & Venezuela) has been plentifully documented. In fact also for the French and English Caribbean Native American slave trade has been documented. Reaching all the way north to even Canada actually! See also:

I am not sure to what extent such slave voyages have been incorporated already within the database. Of course again this enormous project is very much a work under progress. But it would be very useful if eventually this aspect of Intra-American Slave trade will also be featured more prominently on the website. The team behind the Slave Voyages website has already announced praiseworthy plans to also cover domestic slave trade for the USA and Brazil, despite inherent difficulties:


We certainly intend to incorporate maritime slave voyages within the United States and Brazil, whether riverine or coastwise, where such records exist. We also intend to add data on overland migrations where records exist to document “slave coffles” or other overland migrations in a format compatible with the “voyage” structure of the database. For Brazil this seems feasible, because the law required slave traders to register with authorities in Rio de Janeiro before marching inland (creating documents akin to port records), leaders of the caravans were appointed (akin to ship captains), and these forced marches tended to follow repeated routes and pass through checkpoints making them traceable.

For the domestic traffic in the nineteenth-century United States, it is less clear that systematic records will allow for the creation of such an overland voyage-based dataset.Scholars such as Michael Tadman, who have worked to quantify the U.S. domestic slave trade, have relied on different methodologies to estimate the scale of the forced migration—such as tracking changes in census data. That methodology has provided crucial insight on the U.S. traffic, but is not well suited to a database of voyages” (quote taken from “Coverage of the Intra-American Slave Trade“)


Coverage of slave trade within the Indian Ocean area should also be very beneficial! Especially for mixed Afro-descendants in South Africa and the Indian Ocean islands of Mauritius, Réunion, Seychelles etc.. And in fact this is also already under preparation!


Using the Slave Voyages model — scholars working together, sharing data — the International Institute of Social History in Amsterdam is now in talks to create a similar database examining slave trade in the Indian Ocean and maritime Asia.”


Furthermore the website also has an extremely valuable section focused on the actual identities of African captives: African Names Database.  And apparently also this section will be extended in the near future! For more details watch the introductional video by Henry Louis Gates Jr.  posted on the homepage of the Slave Voyages Database. Or also read this article:

7 I sincerely hope the author does not mind the reproduction of these highly educational quotes and overviews from his wonderful book. Naturally no disrespect intended at all! I will retract the screenshots from this blog when requested to do so. Again it is merely for the benefit of my readers that I am including these screenshots. All credits naturally go to the author’s works:





7 thoughts on “Slave Voyages: not only Trans-Atlantic but also Intra-American!

    • Thank you for your groundbreaking research! It continues to be meaningful to me and many others. Thanks also for leaving a comment on my blog I truly appreciate it!


      • When did the usa stop importing slaves ?
        I’m figuring out when the importation for slaves from Northern Gabon stop ?
        Is it possible the Us states like Louisiana, Mississippi, Alabama were still illegally importing slaves to those states ?


        • Have a look on this website:

          The Abolition of the Slave Trade: The Forgotten Story

          Also you might find more answers in this book. I have not read it myself yet but it should feature the most recent research!

          The Last Slave Ships: New York and the End of the Middle Passage (John Harris, 2020)

          Btw. Central African slave trade in this period is known to have been carried out overwhelmingly from moderday Angola and both Congos. Northern Gabon is not a very likely area of provenance. Because for all I know only small numbers of captives from within Gabon were exported as this country still is nowadays very thinly populated and heavily forested. See also this map taken from Harris (2020).

          Liked by 1 person

          • I found out that it’s been estimated that 2,300 Gabon slaves made it to the United States.

            I think they were sent to states like Alabama, Louisiana, Florida, etc.

            Liked by 2 people

  1. Wow, this is such an extensive blog that I had to marinate not about this but the answer you posted to me in response to what I posted to you.

    So after reading your response to me, I did two things:

    First, I looked at my aunt’s updated results. I found that she had no “Benin and Togo” in her results! That was interesting in light of the fact that I have 11% myself. I know that my test is autosomal so it both parents but I figured she would have some but she didn’t. So looking at what you said about how AncestryDNA is having a hard time distinguishing between Ghanaian and Benin and Togo DNA profiles, this enlightens my understanding more and answered my questions about the Yorubas that I asked you.

    The second thing I did with that in mind is checked my matches for Nigerian born test takers. It’s weird because since they got rid of the matches under 8 cM, I actually got more matches who are Europeans! However, I found 2 matches that are potentially Nigerian immigrants. I believe they’re closely matched(one is 21 cM and the other is 11 cM and they have the same last name) and another weird thing is that both of them have Genetic Community matches to Early Virginia African Americans, the one with 11 cM also has Maryland, Virginia and The Carolinas as a community. As you know though, there’s a vibrant Community of Nigerian immigrants in Maryland and the one with 11 cM is from Baltimore. So this means they’re most likely Igbo.

    So reading this post, I feel more enlightened about the roots of my family which is what all my researching is about. Thank you for doing this.

    I forgot to mention that my aunt has 9% “Ivory Coast and Ghana” which is 3% more than my new results.

    Liked by 1 person

    • Thank you for the appreciation! And congratz on finding those Nigerian matches. That is very useful indeed. Quite special also to find a close match with shared DNA greater than 20cM. This is rather uncommon because usually African DNA matches tend to be smaller sized, in line with dilution across the generations. If you happen to have any other shared matches with this particular person (check tab “shared matches”) it could give you valuable leads for follow-up research. If you scroll down to the last section of this blog post below you will find some tips on how to determine a plausible background of your African matches based on either regional admixture or surnames.

      African DNA matches reported for 30 Jamaicans on Ancestry (scroll down to section 8: Methodology)

      another weird thing is that both of them have Genetic Community matches to Early Virginia African Americans

      Actually many Africans get assigned to genetic communities which are designed for African Americans or West Indians. This is because this feature on Ancestry is based on matching strength as well as a clustering of your DNA matches. Usually people being assigned to these communities will indeed also have the background as mentioned in the description. Or at least partially so.

      However obviously because of Trans-Atlantic (as well as Intra-American) connections Africans will often also have close DNA matches with Afro-descendants in the Americas. Whenever this goes beyond a certain threshold they will therefore also be included in such communities. Given the historically known strong presence of especially Igbo Nigerians in early Colonial Virginia this occurence is actually quite meaningful and corroborating therefore!


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s