Over the course of the eighteenth and nineteenth centuries, the transatlantic slave trade delivered millions of Africans to American markets but also encountered serious attempts to dismantle what contemporaries called the ‘Guinea traffic’, all of which were eventually successful. One by one, different nations – Britain, Denmark, the United States, Spain, Portugal, France, the Netherlands, Brazil – abolished their slave trades for various reasons. The demolition of the slave trade mainly occurred in the first half of the nineteenth century by the same governments who had created it.Footnote ¹ Moral and humanitarian criticism of what has been described as ‘the cruellest commerce’ was one significant component in the motivation to eradicate the slave trade.Footnote ² But there were always other factors lying behind anti-slave trade sentiment, including economics, political decisions and pragmatic considerations, all of which combined with humanitarian abolitionism, in varying proportions in different countries, to bring about slave trade abolition. Thus one major theme in analysing the ending of various slave trades is the variety of methods deployed in each nation, none of which directly duplicated one another and not all of which were based on sustained humanitarian campaigning.Footnote ³ Another major theme in the history of slave trade abolition was that in most cases – Denmark being an exception, as it was ended by royal decree – a long period of years was necessary to generate favourable political conditions under which abolition could proceed. Proscribing the transatlantic slave trade in any country was never an easy matter: Too many vested interests were at stake and too many arguments and counter-arguments were put forward in discussions and debates on the topic for abolition of the slave trade to proceed rapidly.

This book takes account of these broad themes to investigate the abolition of the transatlantic slave trade in one country, the United States, which was a significant recipient of slaves for over a century and a half, first as a set of British colonies and later as an independent nation. The United States ended slave importation by congressional action in a law that came into effect on 1 January 1808. The passage to this outcome was a long and somewhat erratic affair, with plenty of individual colony and state proscriptions preceding it over several decades. The entire process has only attracted one monograph, written well over a century ago by a celebrated author. The author and the book in question is W.E. B. Du Bois’s The Suppression of the African Slave-Trade to the United States of America, 1638–1870, published as the first volume in the Harvard Historical Studies in 1896. This was a revision of a Harvard University PhD dissertation, awarded the year before – the first North American doctorate on the slave trade.Footnote ⁴ Drawing upon records such as colonial, state and national statutes, congressional documents, reports of abolition societies and personal narratives, Du Bois divided his book into seven chapters dealing with restrictions on slave imports to the British North American colonies and the United States before 1808 and four chapters examining the international slave trade in relation to the United States between 1808 and 1870. The book is mainly a factual narrative, and it is still cited today by scholars as I do myself in the pages here.

Since Du Bois published his pioneering book, many new sources have become available to historians on the abolition of the slave trade to the United States. Numerous scholars have used some of these materials to publish their findings on one or another aspect of the subject, but there has been no monograph on proscribing slave imports into the United States, and its colonial antecedents, since Du Bois wrote on the topic. This book is an attempt to provide such a fully comprehensive study, which is based on sources used by Du Bois but which ranges much more widely to cover important material, in both printed and manuscript form, that was unavailable to him. Thus, my study includes material drawn from the personal papers of Americans who played an instrumental role in the moves towards abolition of slave importations; the proceedings of various legislative bodies; petitions and memorials; extensive newspaper coverage; and the material left in abolitionist archives. These primary sources enrich the study of the subject and enable a historian to explore it in more depth than Du Bois was able to do with the materials at his disposal. My time frame, however, differs from that of Du Bois. As mentioned here, he covered material dealing with more than two centuries between 1638 and 1870. My study, by contrast, confines itself to the period from c.1700 to the congressional edict abolishing the slave trade into the United States in 1808. Most of the evidence falls within the period from c.1750 to 1808, when the subject of slave trade abolition was regularly discussed in North America. For the period thereafter, Leonardo Marques’s The United States and the Transatlantic Slave Trade to the Americas, 1776–1867 (2016) has already analysed the relevant material in detail.Footnote ⁵

The online Trans-Atlantic Slave Trade Database, which is now the standard accepted source on quantitative data dealing with the subject, records 389,000 Africans arriving in North America.Footnote ⁶ The great majority of these captives disembarked directly from Africa rather than from the Caribbean.Footnote ⁷ Most of these slaves ended up as plantation workers cultivating staple crops in colonies and states from Maryland southwards, though some enslaved people were also imported in the northern colonies. The numerical and regional distribution of slave arrivals in North America varied over time. Some 72 per cent of the influx of Africans to North America came before 1776. All the imported Africans to the Chesapeake (or Upper South) had arrived by then along with 98 per cent of the slaves taken by the northern colonies. The Lower South (mainly South Carolina and Georgia) was the region that took the highest number of captives. Thus 55 per cent of the Africans coming to the British North American colonies entered via Charleston, South Carolina and (to a much lesser extent) Savannah, Georgia. Another third came to the Chesapeake, primarily to the five river systems of Virginia rather than Maryland. Before 1776, the great majority of slaves were carried by British ships leaving the ports of London, Bristol and Liverpool.Footnote ⁸

Slave imports to North America, as the above paragraph suggests, were heavily concentrated in the Chesapeake and South Carolina. Between 1701 and 1807, South Carolina and Georgia (mostly Charleston) accounted for 209,430 slave disembarkations, the Chesapeake (mostly Virginia) 115,480, the northern states 24,128, and the Gulf states (mostly New Orleans) 16,130. In the narrower period of 1781–1810 South Carolina imported 56,270 imputed slaves, of which 47,404 arrived between 1801 and 1810. These figures are for direct arrivals from Africa. In addition, Africans were taken to North America in an intra-American slave trade after they had been first landed in the Caribbean. The numbers in this branch of the slave trade were much smaller. Between 1701 and 1825 in the intra-American slave trade, 38,171 imputed slaves disembarked in North America, including 18,506 in South Carolina.Footnote ⁹

During the American revolutionary war, North American slave imports fell markedly, but they revived after the peace treaty of 1783. US merchants now assumed greater importance in the slave trade. Most of them were based in Newport, Rhode Island, New York, Boston and Charleston.Footnote ¹⁰ They took slaves to different Caribbean islands as well as importing them to the North American mainland. After 1776, US merchants brought in 61 per cent of all slave arrivals coming directly from Africa whereas the share had been only 8 per cent before 1776. Interestingly, this demonstrates a large increase in the North American participation in the slave trade at a time when the colonies were declaring independence from Britain and trumpeting the values of liberty and equality. Only in the final phase of the slave trade to the United States, when South Carolina reopened the traffic between 1803 and 1807, did British firms recapture a portion of their former market share.Footnote ¹¹

Captives brought to the North American colonies and the United States came from seven major regions in West Africa strung along about 2,000 miles of coast – Senegambia, Sierra Leone, the Windward Coast, the Gold Coast, the Bight of Benin, the Bight of Biafra and West-Central Africa. Every major North American region imported slaves from diverse west African areas.Footnote ¹² Some regions were preferred more than others in supplying slaves for the North American market. The most favoured region was Upper Guinea (comprising Senegambia, Sierra Leone and the Windward Coast), which provided 40 per cent of the arrivals in North America. This was significantly higher than the 10 per cent of captives taken from Upper Guinea in the entire transatlantic slave trade to all destinations. By contrast, very few slaves arrived in North America from the Bight of Benin compared with its contribution to the transatlantic slave trade as a whole. Different regions of North America had different levels of connections with specific African regions. Thus, colonies and states north of the Chesapeake took one third of their slaves from Upper Guinea whereas 35 per cent of the captives entering Virginia and Maryland emanated from the Bight of Biafra.Footnote ¹³

The North American regional distribution of newly imported slaves changed over time. The northern colonies were never major importers of Africans because they lacked plantations and their associated staple crops that accounted for most slave labour. However, slaves were imported on a modest scale north of Maryland and utilised in small groups at ironworks, on farms and as domestic servants.Footnote ¹⁴ Within the northern colonies, New England imported far fewer slaves than the middle colonies. The delivery of saltwater Africans to New England comprised 9.3 slaves per 1,000 residents in the period 1700–20 but minus 6.5 slaves per 1,000 residents by 1760–80.Footnote ¹⁵ In the middle colonies, the ratios were 66.7 slaves per 1,000 residents between 1700 and 1720 but only 1.6 slaves per 1,000 residents between 1760 and 1780.Footnote ¹⁶ Philadelphia and New York merchants were mainly responsible for this branch of slave importation.Footnote ¹⁷ Slave deliveries to the middle and northern states never recovered from the low levels of the American revolutionary war era, and were virtually non-existent after 1780.Footnote ¹⁸

Throughout the southern colonies and states, slavery was essential to operate plantations producing staple crops and the slave trade was a much more important phenomenon than in the northern colonies and states. Slave imports south of Pennsylvania were closely tied to export earnings from staple crops. Virginia was an early importer of significant numbers of slaves for its tobacco plantations. In the mid-1730s, the Virginian planter William Byrd thought the influx of Africans was extensive enough to instil the notion that ‘this Colony will some time or other be confirmed by the name of New Guinea’.Footnote ¹⁹ This never occurred, however, because Virginia’s slave trade levelled off in the 1730s when a transition from a naturally declining to an increasing slave population began in that region. The slave trade to Virginia then started to decline from about 1740 onwards, with sufficient native-born fertile women sustaining natural increase in the colony’s black population. Maryland had less tobacco-growing acreage and less piedmont or backcountry land suitable for tobacco growing than Virginia. Accordingly, its demand for African labour was lower than in the Old Dominion. The transition from tobacco to grain in the Chesapeake economy by the time of the American revolutionary war reduced demand for slaves as work outside the tobacco sector could be undertaken by white men and women.Footnote ²⁰ As a result of these factors, an importation of 170.6 slaves per 1,000 of population in the Upper South between 1740 and 1760 declined to 72.2 per 1,000 in the subsequent twenty years.Footnote ²¹

By contrast, in South Carolina, which had a plantation system mainly comprising rice growing in swampy coastal areas along with indigo cultivation from the 1740s, the unbalanced sex ratio of African imports, much favouring men over women, along with diseases found in lowcountry areas, hard physical labour and heavy mortality, meant that the slave population decreased naturally before 1750. In the generation before 1776, South Carolina’s slave population and reproductive levels remained low, even when a surplus of births over deaths was achieved. These demographic problems meant that the delivery of slaves to South Carolina was a thriving affair for most of the half century leading up to the American Revolution. The numbers dipped in the 1740s after increased import duties were introduced to stem the fear of slave revolt after the Stono rebellion of 1739 – the most significant slave uprising in North America before the War of Independence – but the flow of slaves increased in the late 1740s. Charleston, in the mid-eighteenth century, became the focal point of entry for Africans entering the Lower South region.Footnote ²²

A further fall in slave imports came with the non-importation regulations of the late 1760s, implemented as a counterblast to British commercial policies towards the North American colonies. Despite these fluctuations, South Carolina easily imported more Africans than its neighbours to the north and south, North Carolina and Georgia.Footnote ²³ South Carolina’s planters became the most wealthy occupational group in North America in the late colonial period when the ‘opulence’ of the Palmetto colony was noted.Footnote ²⁴ Between 1740 and 1760, the Lower South had 263.7 slave importations per 1,000 residents; this fell to 178.5 per 1,000 over the next twenty years.Footnote ²⁵ The revival of rice cultivation after the end of the American revolutionary war and the rapid emergence of long staple cotton production from the early 1790s boosted the demand for slave labour in the Lower South. Not all of this could be met by natural increase, and consequently, as Ira Berlin noted, ‘African slave traders found a welcome reception in Charleston and Savannah’.Footnote ²⁶

North American slave traders were also active in the slave trade. Their significance in the Guinea traffic increased during the eighteenth century. The slaves carried by vessels leaving North American ports increased from 10,000 in the early 1740s to 30,000 in the mid-1760s.Footnote ²⁷ There was then a precipitous fall over the next fifteen years, but the number rose again from 9,000 in the early 1780s to 55,000 by 1808, when the US slave trade was abolished. In the last four-year period of the trade, between 1804 and 1808, the number of Africans taken by slave ships setting out from US ports reached a peak and there are no signs that it would have diminished suddenly if abolition had not occurred.Footnote ²⁸ Many North American merchants found a niche market to trade rum from New England distilleries for slaves in the Gambia, the Sierra Leone estuary and along the Gold Coast.Footnote ²⁹ By 1776–1800 over three-quarters of the captives taken on voyages starting from US ports came from Sierra Leone and the Gold Coast. Between 1800 and 1810 Senegambia, Sierra Leone, the Gold Coast and West Central Africa provided three-quarters of the slaves taken in such ships.Footnote ³⁰

US slave ships took the majority of their slave cargoes to the Caribbean and Spanish America rather than to mainland North America. Apart from slaves delivered to the United States, notably South Carolina, most captives were delivered to non-Anglophone destinations such as the Dutch Americas, the Danish West Indies, Cuba, Puerto Rico and the Rio de la Plata rather than to the British Caribbean. A final dimension of the slave trade involving the United States occurred between 1821 and 1867 when 85,114 slaves arrived in the Americas using the US flag as a symbol of convenience for at least part of their voyage. A caveat is in order, however, because most of the vessels in these voyages were not American owned.Footnote ³¹

Several themes run throughout the book. First, attention is paid to the role of abolitionism in securing the various state proscriptions of the slave trade and the eventual congressional prohibition of the trade in 1808. Abolitionist writings, speeches and networks are considered in each chapter. Their contribution to the ending of the slave trade is weighed up against economic, pragmatic and political decision-making. The extent to which abolitionists established viable networks to influence state legislatures and the federal government is also evaluated. Second, the role of South Carolina as the colony and state most resistant to supporting measures to proscribe the slave trade is explained in relation to the political decisions made by its colonial and state legislatures and the attitudes and interventions of its delegates to Congress from 1789 onwards. South Carolina’s economy was dominated by slave-produced rice production and exports and its society was based on an uncomfortable dichotomy between a wealthy planter elite that held political control and thousands of slaves with no political rights, who formed a black majority in the colony and state. These factors made it difficult for abolitionist ideas to make an impact in South Carolina, for planters’ livelihoods were centred on slave labour.

A third theme in the book is to show that various mechanisms were followed by different colonies and states to end the slave trade: there was no single route to abolition. In some cases, a law was passed; in others, the abolition of the slave trade was written into state constitutions. In still other cases, laws were passed dealing with gradual slave emancipation and it was implied that a legal ending to slavery would also include prohibiting the slave trade. These different ways of handling the slave trade at state level will be explained. A fourth theme comprises the complex role of the new Federal Congress in relation to slave trade abolition after it began proceedings in 1789. Restrained from acting over the slave trade before 1808 by a clause in the US Constitution, Congress nevertheless played an important role in discussing the slave trade and limiting the despatch of US slave trading ships to foreign ports. Under Thomas Jefferson’s presidency (1801–9), Congress came to the fore in debates over the slave trade as the date when it could act on this subject began to approach. The congressional vote in 1807 in favour of closing the slave trade was vital for proscription of the Guinea traffic to take place.

The book is divided into five chapters. Each covers a chronological period of varying extent, but the issues dealt with are thematically analysed or presented as part of a multi-layered narrative. The structure allows for the abolition of the slave trade to the United States to be covered as a sequence of actions and decisions over time, thereby facilitating the process as a matter of proscription by degrees on a step-by-step basis. Thus, the structure and content of the chapters reflect the incremental stages through which ending the slave trade was achieved. In each period covered by the chapters, many ideas and attitudes expressed on the slave trade were replicated but with significant alterations as unexpected events and changes in political institutions affected consideration of the subject. New scrutiny was also added to the evaluation of the operation of the slave trade over time. The book analyses why it was not until 1808 that a federal proscription of slave imports into the United States could occur but also why the ban on the US slave trade was then ushered in quickly, almost in one fell swoop.

The first two chapters analyse restrictions of the slave trade before the Constitutional Convention of 1787 and also the actions that were set aside or blocked by legislatures and British institutions. Chapter 1 shows that it was common for individual colonies to restrict the level of slave imports by raising import duties on slaves – effectively local taxes – from the first decade of the eighteenth century through to the imperial crisis of the mid-1770s. Some colonies, such as Virginia and South Carolina, were particularly active in raising such duties but many other British North American colonies also did so. The monies raised were used for various purposes ranging from improvements to infrastructure to support for white immigration. But the British Crown, Privy Council and Board of Trade had the constitutional right to veto laws dealing with import duties on slaves, and they frequently exercised this prerogative.

Chapter 2 shows that there was considerable progress achieved in banning the slave trade to some states between the introduction of the Coercive Acts in 1774 – four laws intended to punish Massachusetts for the Boston Tea Party – and the convening of the Constitutional Convention. Virginia, Maryland, Pennsylvania and Massachusetts all prohibited slave imports within a few years of one another in this period. Attempts were made to proscribe slave imports to North America under the two Continental Congresses, but these lacked the political authority to enforce this measure. The same was true of the Confederation governments. Quakers were among the anti-slave trade groups raising concerns about the immorality of the slave trade in the 1770s and 1780s, but they had insufficient influence across the new American nation to secure their goals. South Carolina’s legislature was involved in continuing debates and disagreements over the slave trade between 1783 and 1787, and it became crystal clear that the Palmetto state’s politicians were unwilling to surrender their political control over decisions about whether to open and close Charleston as the main receiving port for enslaved Africans in the state.

Chapter 3 focuses closely on the years 1787–8 when the subject of the slave trade became a matter of discussion and debate at the Constitutional Convention in Philadelphia and during the ratification process in a number of states. The chapter considers the diverse views about the slave trade expressed in these forums and why the subject was so acrimonious. Consideration of the slave trade raised fundamental issues about regional differences between the northern and southern states, the allocation of political responsibility for this matter between the new federal government and the states, the weighing up of economic versus moral aspects of the topic, and the relationship of slavery and the slave trade to the political trajectory of the new nation. In the end, the political debates of 1787–8 incorporated the slave trade as a potential issue to be decided by Congress at federal level. At the time, of course, no federal authority existed to deal with this matter. A clause was inserted in the Constitution (Article 1, Section 9) that expressly forbade any congressional action over the slave trade for twenty-one years, backed up by another section (Article 5) that disallowed any repeal of that clause. The Constitutional Convention and the state ratification debates were the first time that the slave trade had been debated by political delegates from most of the states – first behind closed doors during the Convention and then in public as part of the ratification process. The detailed opposing views expressed indicated that the matter of what to do about the slave trade still needed many further debates before it was settled.

Chapter 4 examines the early years of federal government in the United States from the convening of the First Federal Congress in 1789 until Jefferson’s Louisiana Purchase in 1803 persuaded South Carolina to reopen its slave trade to supply additional slaves to western territories. The initial focus on the slave trade in this period witnessed the presentation of several Quaker petitions to Congress on the subject and the ensuing debates over the slave trade in the House of Representatives. These were divisive discussions, with the Lower South representatives standing firmly behind the constitutional protection for the slave trade until 1808. The leading American statesman James Madison, in particular, wanted to avoid controversy over the slave trade just when Congress was finding its feet on important national political issues. The decision to place those petitions on the table of the House meant that their contents were acknowledged but they were not taken up further at this juncture. Abolitionists turned, from 1791 onwards, first to pressing for more regulation of the participation of US citizens in the foreign slave trade, and also for organising abolition societies in different North American cities under the leadership of the Pennsylvania Society for the Abolition of Slavery. Two congressional acts, in 1794 and 1800, tightened regulations about the participation of US citizens in the slave trade, bringing in penalties for those flouting the new rules; but difficulties occurred in enforcing these laws. South Carolina, the state objecting most to any national proscription of the slave trade, continued laws to keep its own slave trade closed throughout the whole period between 1789 and 1803. It was able to do so because of constitutional protection but the decision for repeated closures was not unanimously supported at state level.

The final phase of the struggle to proscribe the US slave trade is covered in Chapter 5, which concentrates on the complicated means through which South Carolina reopened its slave trade and the action taken by Congress to prohibit the slave trade at national level at the first available opportunity. South Carolina’s state politicians were divided about whether to reopen the slave trade to the state in 1803 but they did so, after some narrow votes in the state legislature, to take advantage of sending new enslaved Africans to the territories carved out of the Louisiana Purchase. Annual debates in South Carolina in 1804, 1805 and 1806, with slim majorities for maintaining an open slave trade, reflected opposing views on the course of action to proceed. At the federal level, Thomas Jefferson’s presidential message of December 1806, exhorting Congress to proscribe the slave trade at the earliest opportunity was heeded and both houses of Congress prepared legislation to this effect in 1807. In the debates over the proposed laws, much more attention was paid to the mechanics of the legislation and to the penalties for breaking the law than to the morality of the slave trade. From 1 January 1808, slave importations to the United States were forbidden by law in the first important congressional intervention over anything connected to slavery in the nineteenth century. This was possible because the slave trade had been cordoned off from slavery in the Constitution, which meant that it could be prohibited without any tampering with slavery itself. This was a necessity in 1808, when there was no prospect of slave emancipation happening either soon or at all.