John Snow's map of the 1854 London cholera outbreak was revolutionary in that it clearly drew a visual connection between deaths and the locations of well pumps. It helped convince authorities that cholera was a water borne disease and effectively created the field of epidemiology.
I'll reimagine the making of this map to even more directly connect the fatalities to the wells, using some GIS tools to estimate walkable neighborhoods served by each well, aggregate the fatalities within each neighborhood, and visualize the wells by that aggregate. Connecting two separate phenomena that aren't actually all that separate.
Here is a link to the finished map: adventuresinmapping.files.wordpress.com/2023/12/johnsnowcholeramap.png
0:00 Lets take a look at the amazing original map
1:28 How to overlay the original map and a GIS basemap at once (and change its color!)
2:20 The visual (and moral) problem of overlapping data points
3:13 Slightly shuffling the visual placement of overlapping points (for the greater good)
4:41 Creating walkability zones around water pumps
7:11 Aggregating cholera deaths into water pump neighborhoods
7:46 Transferring these aggregates to the water pump points
8:43 Visualizing water pumps as vertical extrusions
11:07 Creating a shadow effect for the extrusions
11:52 Making a monochromatic minimalist basemap
13:10 Visualizing uncertainty by making boundaries wavy
14:00 Creating a layout
14:46 Adding graphical label and title
16:56 Visiting the garden and feeding the rabbit some kale
Here are some intro and closing thoughts about this sort of undertaking: adventuresinmapping.com/2023/12/07/john-snows-cholera-map-reimagined/
Check out some other social channels where I share how-to's and updates on random map adventures:
adventuresinmapping.com
www.esri.com/arcgis-blog/author/j_nelson/
John_M_Nelson
johnmnelson
www.linkedin.com/in/johnmnelson/
6 дек 2023
