Update: Thanks to our enthusiastic readers, I’ve update the post to include a new paper on Economic Maps, and a great data viz using WWII maps from the LOC (that was made after seeing this post!)
When we think of collecting data from archives, we are typically thinking of collecting data from books that are in the form of text or numbers — flipping to find the tables of railway revenues or lists of soldiers stationed in a particular area during wartime. But another important source of data in HPE come from images, such as maps, atlases, or even historical data visualizations.
[For those impatient readers, feel free jump to the end and you’ll find links for historical map databases!]
Our academic forefathers knew the power of visual storytelling — readers of this blog most likely remember Minard’s time series graphic of Napoleon’s disastrous campaign against Russia in 1812-13 (data from six variables, all in one image) or others from Minard. Our Broadstreet header, which is Jon Snow’s cholera map, is another example. You’d be surprised at how many you can find in the archives.
Equally impressive are the infographics from W.E.B. Du Bois and his team of sociologists, whose data visualizations helped present racial disparities for African Americans in the US and abroad. (The book looks gorgeous, too).
Importantly, historical maps or atlases are so much more than just geographic. They can be a tremendous source of data. For example, take fire insurance maps — if you weren’t writing a paper on insurance, maybe you would yawn and pass these books on by.
But these “Sanborns” are atlases that provide detailed rendering of US cities and neighborhoods. Used to help insurance companies assess liabilities, these maps also document building materials and infrastructure, property lines and land use restrictions, public good provision data (sprinkler systems, fire hydrants, gas and water mains), other elements of the city (churches, schools), and how urban geography has changed over time. These might be the control variables you have been dreaming of! And in addition to the Sanborn collections of the Library of Congress, luckily there are also a zillion of them on the web.
Also don’t forget the beauty of working with historical maps in ArcGIS. Once you have an image of a scanned map, you can georeference it and use GIS software to present your data. Increasingly more historical shape files are becoming available (see here and here). For those new to georeferencing, you can check out this tutorial from UPenn, an open access textbook on geospatial history, or Harvard’s list of GIS resources. There’s even an ArcGIS version of Jon Snow’s cholera map (click here)!
UPDATE: After this post went up, Björn Brey kindly pointed out the existence of this great paper in the Journal of Economic Perspectives called the “Economics of Maps” (by Abhishek Nagaraj and Scott Stern). Happy reading!
But finally, be cautious — while it’s immensely exciting to find historical data, maps (like any data) might not be accurate. The picture below shows the “Mountains of Kong,” an impressively formidable mountain range in Africa that appeared in maps in the 18th and 19th centuries. Except these mountains didn’t exist — they were the byproduct of one explorer’s account, and then cartographic spillover.
FINDING THE MAPS
Seriously, what are you waiting for? Take your area + time period, and go poke around. Here are some links to get you started:
1. Library of Congress, Map Collections, https://www.loc.gov/maps/collections/
Maps and Charts of North America and the West Indies, 1750-1789? Railroad Maps, 1828-1900? Maps of Liberia, 1830-1870? Troop positions in WWII? Check.
Update: Also, after this post went up, we were sent this great data viz by Jeff Allen, who animated a series of maps from 1944 at the LOC links we provided! Great stuff.
2. David Rumsey Map Collection, David Rumsey Map Center, Stanford Libraries, https://www.davidrumsey.com
This historical map collection has over 105,000 maps and related images online. Make sure to check any copyrights!
3. Old Maps Online, http://www.oldmapsonline.org/about/
No kidding, that’s what it’s called. But it’s a digital historical cartography initiative that has a searchable database, and its “About” section details the participating libraries (with links, so you can go directly there).
4. UT Austin’s Perry-Castañeda Library Map Collection.
Check out their geospatial database collection (https://geodata.lib.utexas.edu). And then huge props to UT Austin for compiling pages and pages of historical maps online. Librarians are the best. See http://legacy.lib.utexas.edu/maps/map_sites/hist_sites.html.