The Trans-Atlantic Slave Trade: A Database on CD-ROM

Published by EH.NET (October 2000)

David Eltis, Stephen D. Behrendt, David Richardson, and Herbert S. Klein,

The Trans-Atlantic Slave Trade: A Database on CD-ROM. Cambridge and New

York: Cambridge University Press, 1999. (User guide, xi + 89 pp.) $195, ISBN:

0-521-62910-1.

Reviewed for EH.NET by Lorena S. Walsh, Department of Historical Research, The

Colonial Williamsburg Foundation.

The Trans-Atlantic Slave Trade Database is a monumental achievement

that brings together in a single multisource data set the results of over

thirty years of international research undertaken by many individual scholars

working in English, Portuguese, Danish, French, Spanish, and Dutch on the

largest transoceanic migration of any people prior to the outpouring of

Europeans to the New World in the nineteenth century. The authors entertain

“grand hopes” for this extraordinary resource, sponsored by the W.E.B. Du Bois

Institute at Harvard University with additional support from the National

Endowment for the Humanities, the Mellon Foundation, and the Ford Foundation,

and taking seven years to complete. It will, they contend, not only “enable

historians to develop new insights into the history of peoples of African

descent and the forces that determined their forced migration,” but will also

“greatly facilitate the study of cultural, demographic, and economic change in

the Atlantic world from the late sixteenth to the mid-nineteenth centuries”

(p. 2). Are the hopes of the authors, the sponsors, and of Cambridge

University Press justified? Or is the publication of this database more likely

simply to facilitate an expansion of the esoteric and sometimes contentious

numbers games that have frequently characterized slave trade studies? My sense

is that the project is indeed likely to stimulate new research not just on the

slave trade narrowly conceived, but also on a range of broader economic,

demographic, and cultural issues on both sides of the Atlantic.

The database includes records of 27,233 trans-Atlantic slave ship voyages made

between 1595 and 1866, accounting for between two-thirds and three-quarters of

all trans-Atlantic slave voyages sailing after 1600. (Independent estimates of

the volume of the trans-Atlantic slave trade after 1600 yield a “scholarly

consensus” figure of 11.4 million departures from Africa and 10 million

arrivals in the Americas. This suggests a total of between 34,482 and 35,561

slaving voyages in this period.) The authors standardized existing data sets

compiled by individual researchers, collated voyages that appeared in several

different data sets, and added new information from previously unexplored

sources. Extraordinary care was used in the initial compilation and in

subsequent editing of the database; the portion that I have used (and

rechecked against original primary sources) is exceptionally accurate.

Coverage of the British trade is fullest (the authors estimate that 90 percent

of all voyages are included) and the eighteenth-century French and Dutch

trades are also largely complete. Bigger gaps exist for the Portuguese,

seventeenth-century French, and nineteenth-century Spanish, Danish, and North

American trades. However the authors contend that the set “provides samples

large enough to present the major trends over time” (p. 5).

Each entry in the database consists of a single slaving voyage, for which up

to 226 pieces of information may be available. These include 162 data

variables incorporating information collected from the sources such as dates

at which the ship left from or arrived at various destinations during the

voyage; ports of origin, slave purchase, and delivery; number of slaves

embarked and disembarked, their demographic composition and mortality levels;

details of ship construction, registration, armament, and crew size; names of

captains and owners; the outcome of the voyage; and archival sources. An

additional 64 imputed variables are calculated or imputed from the data to

compensate for missing information and to facilitate analysis by consolidating

or regrouping variables that have unwieldy numbers of individual codes. These

include consolidation of geographic locations into regional and continental

categories, and grouping of voyages into different temporal categories (year

the voyage originated, year in which slaves were embarked, and year of

disembarkation, and for the last also into periods of 5, 25, and 100 years).

Outcomes of voyages (successful completion, wreck, capture, or insurrection

somewhere en route, etc.) are reclassified in three ways from the perspective

of slaves, captors, and owners. Other inferred variables group locations into

major trading regions, estimate the numbers embarked or disembarked where full

information is not available, and regroup data on age, sex, and mortality. How

the estimations were made is clearly documented (the SPSS program that

creates the imputed variables is included on the CD-ROM), so users can easily

substitute different groupings or estimations.

The usefulness of the database for refining conventional slave trade studies

is obvious, but it is the broader applications that go well beyond core issues

such as the volume and demographic structure of the trade, Middle Passage

mortality, and shipping productivity — indeed far beyond the slave trade

itself — that are the most exciting. On the African side, data on slave

exports from specific coastal outlets afford insights into the slave and

commodity trades of particular African subregions and even single ports, and

into African agency through resistance to the trade as evidenced in ship

insurrections, as well as broader economic and demographic results. The

authors contend that “the large role of Africans in the Atlantic world” is

“perhaps the single most important preliminary feature to emerge from these

new data” (p. 35). As the largest data base on any transoceanic trade of the

seventeenth and eighteenth centuries, it facilitates research into European

long-distance shipping activities, including investigations of changing

shipping technologies and, from records of ports of origin, ship owners, and

captains, connections between the slave and other colonial trades. For the

Americas, new information on the numbers and demographic composition of forced

migrants brought to particular destinations suggests a need to reassess

current understanding of at least some local population histories. Even more

importantly, the data set makes available more precise information on which

parts of Africa supplied the different parts of the slaveholding Americas.

Expanded evidence on the African origins of forced migrants will allow

scholars to explore the impact of African heritage on New World societies, and

to better assess patterns of cultural retention and adaptation. Most of the

papers and articles initially derived from the data set (listed on pp. 55-56)

deal with traditional slave trade topics. However David Eltis’s The Rise of

African Slavery in the Americas (Cambridge University Press, 2000) —

which builds on the database — provides a striking example of how such

quantitative measures can be utilized in combination with qualitative

materials to address broader comparative economic and cultural issues

including topics such as gender, ethnicity, and value systems.

Unlike many digitized data sets available through sources such as ICPSR that

require some level of technical expertise to manipulate, the data on

individual voyages can be readily accessed, queried, and rearranged, some

basic analyses obtained, and the results graphed, viewed on interactive maps,

and printed out simply by clicking on pull-down menus. Selected subsets can be

saved for subsequent reference or downloaded into SPSS data files for

modification and more refined analysis according to individual needs or

preferences. Thus the database has importance for several different audiences.

Scholars interested in quantitative aspects of the trans-Atlantic slave trade

are but the most obvious group. It is also a readily accessible reference work

that ought to be available to non-specialist as well as specialist users of

college and museum libraries. Finally, it is a marvelous teaching resource,

both for supplementing other course materials and from which students with

varying levels of technical expertise can develop a wide range of research

projects.

A closing caveat is perhaps in order since my enthusiastic endorsement of

The Trans-Atlantic Slave Trade Database is definitely not that of a

disinterested reader or casual user. Invited to present a paper exploring a

subset of the database pertaining to the Chesapeake region for a conference

held at Williamsburg in 1998, I at first imagined that this would entail

little more than a cursory review of some revised numbers. That supposedly

limited foray has since expanded into a multi-year research project

incorporating additional information on Chesapeake slaving voyages; tracing

connections between the slave, indentured servant, and tobacco trades;

exploring social, demographic, and cultural implications for the region; and

developing museum interpretations underscoring trans-Atlantic

interconnections. My experience is surely not unique. An example of a related

project is Gwendolyn Midlo Hall, ed., Databases for the Study of

Afro-Louisiana History and Genealogy, 1699-1860: Computerized Information from

Original Manuscript Sources (Louisiana State University Press, 2000).

Until recently compilations of slave trade statistics have seemed to reduce

one of the darkest episodes in world history into a set of abstract and

bloodless figures. This commendable collaborative effort now offers scholars

not only an authoritative source for developing better statistics, but also an

extraordinary resource from which to begin translating those esoteric numbers

back into a more humanized history.

(System requirements: The following configuration is recommended to run the

CD-ROM: Windows 95, 98, or NT operating system; 166 MHz Pentium processor; 32

MD RAM; 800 x 600 monitor resolution x 65,536 colors (16 bits); 6x speed

CD-ROM drive; 84 MD available hard disk space.)

Lorena S. Walsh is the author of From Calabar to Carter’s Grove: The

History of a Virginia Slave Community (University of Virginia Press,

1997), and of “The Chesapeake Slave Trade: Regional Patterns, African Origins,

and Some Implications,” William and Mary Quarterly, forthcoming,

January 2001.