Methodology

Africa’s Imperial Commodities uses available data on commodity exports to explore the history of African and European trade relationships. The data for the website comes from the African Commodity Trade Database (ACTD) published as:

Frankema, Ewout, Jeffrey Williamson and Pieter Woltjer. “An Economic Rationale for the West African Scramble? The Commercial Transition and the Commodity Price Boom of 1835-1885.” The Journal of Economic History 78, no. 1 (2018): 231-267.

Data

The most robust dataset in the ACTD includes information on fourteen commodities that moved between Africa and Europe in the nineteenth and early twentieth century. The dates are important because the data begins with the British abolition of the slave trade in 1807. The information collected as part of the ACTD, then, reflects the era of so-called legitimate trade. The term legitimate trade signaled a shift in the focus of European trading engagements with Africa from enslaved persons to commodities. While this digital project focuses on commodities, it is important to note that the slave trade and slavery continued.

By the end of the nineteenth century, legitimate trade continued under the economic development policies of the colonial regimes. Colonial states encouraged the export of financially valuable commodities in their territories. The states contributed to the export of commodities by investing in transportation networks and coercing labor, for example. However, it was the initiative of African producers and traders that drove commodity exports during the colonial period, as they had during the era of legitimate trade.

The dataset used in Africa's Imperial Commodities includes information from the era of legitimate trade and from the colonial period. There are more than nine thousand observations, where each observation includes annual statistics for a single commodity. These statistics include information about the quantity, cost, and place of export. The dataset was compiled from the Colonial Blue Books, the Statistical Abstracts for the United Kingdom, the Tableau General du Commerce de la France, and the Annual Statements of Trade for the United Kingdom. Data entry was completed by the Rural Environment History Group at Wageningen University. You can read more about its construction in this published journal article.

Processing

The data that features in Africa's Imperial Commodities originated in the ACTD dataset. The data was subset into indivudal commodity tables that contain records with quantities in metric tons. The exclusion of non-metric observations was necessary to standardize the data used in the visualizations. Otherwise, it would not have been possible to analyze historical trends or to compare exports from different colonies. You can read more about how processing affects the visualizations on each of the commodity pages. The commodity tables were then transformed into JSON files and uploaded into the website. R, a language for statistical analysis, was used to process and transform the ACTD dataset.

The website features two types of visualizations, scatterplots and barcharts. The scatterplots display all commodity observations with metric conversions, even for multiple observations in the same year. Meanwhile, the barcharts display annual export quantities for single colonies. Both visualizations were created using D3.JS, a JavaScript library.

Limitations

The ACTD was compiled from historical documents at African export and European import points. The documents offer brief snapshots of commodities that traveled on commercial ships between the two continents. However, the documents say little about the movement of the commodities within Africa or Europe. Because of this, Africa's Imperial Commodities relies on secondary sources to explore how internal changes affected the quantity of exports captured in the ACTD.

Moreover, the information conatined in the ACTD was collected by European officials at customs locations along the African and European coastline. The descriptions, geographical areas, quantities, and monetary values reflect the conceptions of the officials and the larger political-economic system of which they were a part. Africa's Imperial Commodities maintains the concepts and categories used by the record keepers. However, there are other ways to approach the data, including investigations into the perspectives of African traders and producers. This website does not pursue those inquiries.