“After nearly 10 years as physical media, SlaveVoyages was introduced to the public as a website in 2008 and then relaunched in 2019 with a new interface and even more detail. As it stands today, the site, funded primarily by grants, contains data sets on various aspects of the slave trade: a database on the trans-Atlantic trade with more than 36,000 entries, a database containing entries on voyages that took place within the Americas and a database with the personal details of more than 95,000 enslaved Africans found on these ships.
The newest addition to SlaveVoyages is a data set that documents the “coastwise” traffic to New Orleans during the antebellum years of 1820 to 1860, when it was the largest slave-trading market in the country. The 1807 law that forbade the importation of enslaved Africans to the United States also required any captain of a coastwise vessel with enslaved people on board to file, at departure and on arrival, a manifest listing those individuals by name.
Countless enslaved Africans arrived at ports up and down the coast of the United States, but the largest share were sent to New Orleans. This new data set draws from roughly 4,000 “slave manifests” to document the traffic to that port. Those manifests list more than 63,000 captives, including names and physical descriptions, as well as information on an individual’s owner and information on the vessel and its captain.
Because of its specificity with regard to individual enslaved people, this new information is as pathbreaking for lay researchers and genealogists as it is for scholars and historians. It is also, for me, an opportunity to think about the difficult ethical questions that surround this work: How exactly do we relate to data that allows someone — anyone — to identify a specific enslaved person? How do we wield these powerful tools for quantitative analysis without abstracting the human reality away from the story? And what does it mean to study something as wicked and monstrous as the slave trade using some of the tools of the trade itself?
Before we go any further, it is worth spending a little more time with the history of the trans-Atlantic slave trade itself, at least as it relates to the United States.
A large majority of people taken from Africa were sold to enslavers in either South America or the Caribbean. British, Dutch, French, Spanish and Portuguese traders brought their captives to, among other places, modern-day Jamaica, Barbados, Cuba, Puerto Rico, Brazil and Haiti, as well as Argentina, Antigua and the Bahamas. A little over 3.5 percent of the total, about 389,000 people, arrived on the shores of British North America and the Gulf Coast during those centuries when slave ships could find port.
In the last decades of the 18th century, moral and religious activism fueled an effort to suppress British involvement in the African slave trade. In 1774, the Continental Congress of rebelling American states adopted a temporary general nonimportation policy against Britain and its possessions, effectively halting the slave trade, although the policy lapsed under the Confederation Congress in the wake of the Revolutionary War. Still, by 1787, most of the states of the newly independent United States had banned the importation of slaves, although slavery itself continued to thrive in the southeastern part of the country.
From 1787 to 1788, Americans would write and ratify a new Constitution that, in a concession to Lower South planters who demanded access to the trans-Atlantic trade, forbade a ban on the foreign slave trade for at least the next 20 years. But Congress could — and, in 1794, did — prohibit American ships from participating. In 1807, right on schedule, Congress passed — and President Thomas Jefferson, a slave-owning Virginian, signed — a measure to abolish the importation of enslaved Africans to the United States, effective Jan. 1, 1808.
But the end to American involvement in the trans-Atlantic slave trade (or at least the official end, given an illegal trade that would not end until the start of the Civil War) did not mean the end of the slave trade altogether. Slavery remained a big and booming business, driven by demand for tobacco, rice, indigo and increasingly cotton, which was already on its path to dominance as the principal cash crop of the slaveholding South.
Within a decade of the invention of the cotton gin in 1793, annual cotton production had grown twentyfold to 35 million pounds in 1800. By 1810, production had risen to roughly 85 million pounds per year, accounting for more than 20 percent of the nation’s export revenue. By 1820, the United States was producing something in the area of 160 million pounds of cotton a year.
Fueling this growth was the rapid expansion of American territory, facilitated by events abroad. In August 1791, the Haitian Revolution began with an insurrection of enslaved people. In 1803, Haitian revolutionaries defeated a final French Army expedition sent to pacify the colony after years of bloody conflict. To pay for this expensive quagmire — and to keep the territory out of the hands of the British — the soon-to-be-emperor Napoleon Bonaparte sold what remained of French North America to the United States at a fire-sale price.
The new territory nearly doubled the size of the country, opening new land to settlement and commercial cultivation. And as the American nation expanded further into the southeast, so too did its slave system. Planters moved from east to west. Some brought slaves. Others needed to buy them. There had always been an internal market for enslaved labor, but the end of the international trade made it larger and more lucrative.
It is hard to quantify the total volume of sales on the domestic slave trade, but scholars estimate that in the 40-year period between the Missouri Compromise and the secession crisis, at least 875,000 people were sent south and southwest from the Upper South, most as a result of commercial transactions, the rest as a consequence of planter migration.
New, more granular data on voyages and migrations and sales will help scholars delve deeper than ever into the nature of slavery in the United States, into specifics of the trade and into the ways it shaped the political economy of the American republic.“