Johannes Postma is a Dutch-born American historian and Professor Emeritus of European and African History at Minnesota State University, Mankato. Among those drawn to African history with the U.S. Civil Rights movement, he was one of a group of international scholars who, in the 1960s, began examining archival records of the trans-Atlantic slave trade. His 1970 doctoral dissertation, “The Dutch Participation in the African Slave Trade: Slaving on the Guinea Coast, 1675-1795,” was the first comprehensive study of Dutch transatlantic slave trafficking. A quick succession of conference papers and journal articles, including “The Dimension of the Dutch Slave Trade from Western Africa” (1972) and “The Dutch Slave Trade: A Quantitative Assessment” (1974), established him as an authority on Dutch Atlantic slave trafficking.

Publication in 1990 of the results of his two decades of research and study, The Dutch in the Atlantic Slave Trade, 1600-1815 (Cambridge University Press) became “the definitive work in the history of the Dutch slave trade” (Peiter Emmer, Journal of Modern History, (Vol. 64, Dec. 1992; David Eltis, Journal of Economic History, Vol. 51, Issue 2). It remains the benchmark text on the subject.

Postma donated his research data to the Database of Slaving Voyages project collected by Harvard University’s W. E. B. Du Bois Institute, Voyages: The Trans-Atlantic Slave Trade Database. Originally published on CD-ROMs, the collection was expanded into the open-access interactive web site SlaveVoyages developed by David Eltis and other researchers at Emory University, which is updated as new data becomes available. This expansion of data has enabled a shift in focus from the transoceanic voyages themselves to the people involved in the trade—enslavers, traffickers, and enslaved—and has become a resource for tracing the ancestry of African-Americans.