Using Custom Maps in Tableau: Milwaukee Fallout Shelters Map
Tableau and Power BI make it easy to create maps and over lay additional information such as census data, Zip code areas and more. But what if you wanted to use an archival map or map non geographic data such as the cost of seats in a stadium? Well, you can do that in Tableau pretty easily too.
Milwaukee Fallout Shelters is a project intended to showcase custom map making in Tableau by mapping the 1,249 community fallout shelters listed in the “Milwaukee County government family survival plan” (PDF), a special advertising section distributed in the February 15, 1972 editions of the Milwaukee Journal and Milwaukee Sentinel newspapers.
The Community Fallout Shelter Program began in September of 1961. The purpose of the community shelter program was to locate, mark and stock as many fallout shelter spaces as possible.
Many fall out shelter signs are still visible on the exterior of many Milwaukee buildings, including Straz Tower on Marquette’s campus.
Below is an abbreviated break down of the project process. A more detailed explanation can be found in the methodology section on the project website.
Locate the data — Thanks to staff at the City of Milwaukee’s Municipal Research Library who compiled a list of all items in their collection under the subject heading of “Civil Defense.” One of these items was a PDF version of the family survival plan.
Begin data janitoring — Given the poor optical character recognition (OCR) of the PDF and its column layout the addresses were manually entered from the index into an Excel spreadsheet.
Splicing the Map Together — In the family survival plan, the map is spread out over 15 pages. To get the map into Tableau, the map pages were saved as PNG files from the original PDF and spliced together into one large map using Adobe Photoshop.
Create a Custom Map in Tableau — Once the spliced map is imported into Tableau as a background image, you look up X / Y pairs to add new marks to the custom background image. The easiest way to do this is add an annotation by right-clicking on the view, hovering over “Annotate”, and clicking “Point…”. Thanks to Ryan Sleeper’s tutorial on How to Make a Custom Map in Tableau for laying out the steps of this process.
