Using Data Viz to Answer a Historical Question (Updated!)

While the data visualization models on this site are nice to look at and certainly can show people complex statistical information in a more visually appealing way, the true value of these models insofar as they contribute to the historical venture is twofold:

1. Can they help to show us anomalies or changes in the data that have a basis in the historical record?
2. Can they help to explain such anomalies or at least bring us closer to possible reasons why such changes are the case?

As an example to illustrate this point and see if it has merit, we can see in the following model that there is a significant drop in the volume of coolies being transported between 1858 and 1862. 1862 represents the lowest volume of any year, despite it being right in the middle of the trade's development and coming immediately before a huge surge in the coolie trade in the following decade.

So how do we explain this decline in the trade?

Since the data we have can only explain so much, it is beneficial to consider first those major historical events or circumstances that were occurring at the time and how they might fit into the picture:

• Taiping Rebellion- This massive rebellion taking place between 1850-1864 was a major conflict in central China that caused huge demographic shifts as a result of the violence and conflict. However, the migrations that took place forced many Chinese to emigrate to the coastal provinces where the coolie trade was present, and as such helps to explain the rise of available coolie labor, not any shortage of it.
• The 2nd Opium War- This Sino-Western conflict between 1857-60 led to the opening of more Chinese ports to Western merchants. The coolie trade's presence in Chinese ports was often bolstered by that of the opium trade, and therefore the war would help to explain the expansion of the trade, not any decline in the short term.

Since these major historical events don't seem to lend any explanation as to why the coolie trade declined between 1858-62, a closer look at the data itself is warranted. By drilling down the above model by the port of departure, a more complete picture of the coolie trade overall becomes available:

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In this bar chart, each year's volume is broken down by the ports of departure in China. With this breakdown, it is easier to see several pieces of information:

• The consistent dominance of Macao over all other ports in terms of volume
• The decline of Swatow and Amoy as ports of departure following 1858 (and Cumsingmoon's decline earlier)
• The rise of Canton and Hong Kong as ports of departure following 1858

Swatow, Amoy, and Cumsingmoon became less popular ports for transporting coolies due to the unregulated nature of these emigration stations and their close connections with the opium trade that was being conducted from these clandestine stations. According to Arnold Meagher, opium houses pressured their officials on the ground to move their actions to legal ports, and so emigration traffic that was closely associated with the opium trade went with them, helping to explain the rise in Canton and Hong Kong as ports for the coolie trade. (Meagher, 101)

What is not explained in this chart, or in the historical record from what I have been able to find, is why the volume of coolies transported out of Macao dropped precipitously in 1861 and 1862. These two years are anomalies in comparison to the steep rise in the coolie volume in the subsequent years, which resulted from the increased regulations on the coolie trade implemented by the British and Chinese in those ports under their control which caused coolie traders to increasingly relocate their activities to Macao.

One final visualization may aid us is narrowing our focus further. The following visualization is a variation of the previous one, in which coolie trade volume is broken down by the destination:

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In this model, it becomes clear that the decline in coolie volume from 1858-1862 primarily impacted those ships destined for Cuba. In fact, despite the rise in ships going to British Guiana and Peru, volume overall decreased. Thus, we can also look to the situation in Cuba between 1858-62 to help explain the decline in coolies being transported.

Thus, supply (in Macao) and demand (in Cuba) become the two factors potentially driving the decline in these years.

Given that we have not been able to fully answer the question raised by the data, we can say that the data can never fully explain the various historical events and processes underlying it. However, without such visualizations, the question may not have been asked or framed in a way that would lead the historian to focus on the Macao trade between 1861-62 or the situation in Cuba specifically. Data and data visualizations, for the historian, can be incredibly useful tools that complement more traditional forms of "doing" history.

UPDATE: After further research as part of my senior History thesis, I have found a potential explanation for the drop in coolie volume between 1861-62. These years coincided with serious efforts by Lao Chonguang, Governor-General of Guangdong, to eliminate the illicit coolie trade in ports like Whampoa and Swatow. Much of the French activity in these areas actually involved capturing coolies in those ports and shipping them to Macao for further transport to the New World. As such, an impact in the number of coolies captured in Whampoa and Swatow would have an impact on the number of coolies shipped out of Macao. This historical nuance is not visible in the data, which highlights the complex nature of coolie recruitment due to the various international actors involved. It also speaks to the limitations in data to illustrate these nuances.

Sources:

MEAGHER, A. J. (1975). THE INTRODUCTION OF CHINESE LABORERS TO LATIN AMERICA: THE “COOLIE TRADE,” 1847-1874. ProQuest Dissertations Publishing.

Coolie Emigration Flow

These "Alluvial Flow" models show the composition of the flow of coolie laborers from their chinese port of origin to their various destinations in latin america. the thickness of the lines indicate the number/volume of coolies transported.

The significance of these models is twofold.

1. First, they shows that the vast majority of Chinese laborers were destined for Peru or Cuba.
2. Second, they shows that the vast majority of those Chinese laborers transported were processed through the port of Macao, which was a Portuguese-controlled territory during the Coolie Trade and long after its demise.

Thus, these models help to visually explain why the Chinese government was so limited in its control over the trade, since so many coolies were transported out of ports that they did not have jurisdiction in. Canton and Hong Kong also fall under this category of ports outside direct Chinese control. These models also include less significant ports of departure and arrival and help to frame departure and arrival locations in terms of transportation volume side-by-side. 

This second Alluvial model, while much busier and complex, maintains the relative clarity of the Port of Departure and Destination country's volume but causes the flow lines to pass through a 3rd variable (Year). This allows one to see the volume of each year relative to the total volume of coolies being transported. What is lost in this 3 dimension flow is the direct relationships between Port of Departure and Destination Country. The total volume leaving a Port and arriving in a country is preserved, but one can no longer determine the amount of coolies transported from Macao to Cuba, for example. But we can now see which years had the most transport volume and how each port of departure and destination contributed to the volume in a given year.

Raw data from Meagher, Arnold J. 2008. The Coolie Trade : The Traffic in Chinese Laborers to Latin America, 1847-1874. Xlibris Corporation.