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Custom maps for education: Louisiana purchase

Posted 2 years ago
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I wanted an unlabeled map for a geography test, and looking at the web I realized it would be easier to just make a custom map using CountryData. Turned out I had to instead use AdministrativeDivisionData for the US states, and I had to do a web search for the boundaries of the Louisiana purchase, but overall it was pretty simple. The educational context was home schooling elementary age students.

The lesson was combining the learning of the US states with some historical context, and the students were supposed to label the states that had at least a part of them in the Louisiana purchase. A more sophisticated lesson might have been to have the students follow these steps to make the map in the first place.

The first step was to get the polygons for those states.

states = AdministrativeDivisionData[{#, "UnitedStates"}, 
     "Polygon"] & /@ {"Louisiana", "Arkansas", "Missouri", "Iowa", 
    "Minnesota", "Texas", "Oklahoma", "Kansas", "Nebraska", 
    "SouthDakota", "NorthDakota", "NewMexico", "Colorado", "Wyoming", 
    "Montana"};

Then a simple Graphics can show them all.

Graphics[states]

boring-Louisiana-purchase

To get something more reasonable, more arguments were given. Here I made the states white with a gray border. This is relatively low-level so the customization, like text, colors, other graphics, etc is pretty flexible.

Graphics[{EdgeForm[Gray], White, states}]

just-states

I don't know if there is a way within Wolfram Language to get the Louisiana purchase polygon, but I found this on GitHub posted by a Bill Morris. https://gist.github.com/wboykinm/05756ac2e625bae9ed81?short_path=cb9abe4 I downloaded that and used Import. Mathematica interpreted the file and made a nice GeoGraphics object. I didn't want a nice picture for this purpose and just wanted the polygon.

json = Import[(*filepath*)];
Graphics[{{White, EdgeForm[Black], states}, {EdgeForm[Red], 
   Opacity[0], json[[1, 2, 1, 2, 1, 2, 1, 1, 45]]}}]

Louisiana-purchase

There is probably a better way, but I just Extract-ed the Polygons and picked the one that looked right.

Next up, a map for the Missouri Compromise. That will be easier because it is just the states.

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