Steamboats, Yellow Fever, and Making Maps Move
Sunday, July 25, 2010 at 3:18PM
Ian Read


I hope this video, shown recently at BRASA, gives support to several arguments.  The first is that yellow fever most likely appeared in Brazil in 1849 (for the first time in 157 years) because it was transported on ships carrying migrants on route to mine gold or settle in California.  Contemporaries blamed a ship arriving with 49ers as the cause of the outbreak in Bahia, but this is not widely known or discussed by historians today.  In fact, historians more commonly connect the slave trade with the outbreak of yellow fever, although this seems improbable for reasons that I'll save for another post.

Second, yellow fever moved inland both in the United States and Brazil with the help of steam propelled riverboats and locomotives.  See my previous post for evidence that it also followed railroad routes.  

There is an important implication to the disease's dramatic movement.  Yellow fever, cholera and bubonic plague were all absent in Brazil during the first half of the 19th century, but caused hundreds of thousands of deaths during the second half.  Smallpox also worsened in mortality, killing millions.  For the United States, all of these diseases except bubonic plague were present, but were worse during the first half of the century.  Therefore, we should include the changing epidemiological environment with geography and institutions as the main reasons why the development gap between these two countries widened between 1850 and 1900. 

The last argument was methodological, and I hope it became apparent in the video/slide show.  I believe that visually representing spatial data not only gives us the tools to make connections we might not have made otherwise, but it helps build support for our arguments.  It is one thing to say that steamboats preceded outbreaks of yellow fever on the Mississippi, São Francisco and Amazon Rivers, but another thing to show the arrival of the steamboats and outbreaks on a geocoded map changes over a set time period.

Article originally appeared on Era of Epidemics: A Spatial Approach to Disease and History in Imperial Brazil (
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