What Maps Are Not

Calling your attention to two great blog posts by northierthanthou: “A Map is Not a Territory” and “Map Ain’t Time Either.” Both explore the judgments that are made by mapmakers, and how their decisions can mislead readers.

From the first, which discusses differences between a AAA road map that omits “Indian Country” sites and one that is specifically for “Indian Country”:

The issue doesn’t seem to be resolution. The Arizona and New Mexico map has a higher resolution than the one for Indian country. I somehow doubt that anyone hatched a plot to hide Tsaile from Ken. My guess, is that the criteria for selecting what to put on each map simply differs, and that the difference was enough to make Tsaile disappear (along with quite a few other things, actually).

And from the second, which discusses how various maps visualize Native American culture areas:

This placement on teh map isn’t from time immemorial; it begins at the cusp of the 1400s, give or take a bit, and that enables us to place their entrance into a sequence of events for the region. They were still settling into the total territory on this map when the Spanish began exploring the region, arriving well after their Pueblo neighbors. Knowing that helps to put the map in perspective. Not knowing that invites an a-historical reading of the map.

Questions to discuss with students: What do the maps you use in class omit? What do your mental maps omit?  When you’re designing a data visualization, what are the most important factors to consider?  Do click through to read the entire posts, if only to see the maps in question!

At the Intersection of Math, Geography, and Politics

Which would you rather have, a town council made up of at-large members or a town council made up of representatives from specific districts? The first is where each one is elected by the entire town and the second is where a council member is voted for only by residents in that district. If the answer is the latter, then you need to consider how the districts should be drawn.

That’s the work that Professor Moon Duchin at Tufts University is doing: applying research in the field of metrical geometry on mathematical measures of compactness to the problem of drawing political districts. She says:

People just have the idea that it means the shape shouldn’t be too weird, shouldn’t be too eccentric; it should be a kind of reasonable shape. Lots of people have taken a swing at that over the years. Which definition you choose actually has stakes. It changes what maps are acceptable and what maps aren’t. If you look at the Supreme Court history, what you’ll see is that a lot of times, especially in the ’90s, the court would say, Look, some shapes are obviously too bizarre but we don’t know how to describe the cutoff. How bizarre is too bizarre?

When districts are drawn compactly, they are fair.  When they aren’t you get gerrymandering, as in this example:

map showing two discontiguous areas making up one district
Illinois’ 4th Congressional District, 108th Congress

Learn more about redistricting (also known as reapportionment) in WorldView Software’s U.S. Government Map: Massachusetts 4th Congressional District.

[The featured image is the original cartoon of “The Gerry-Mander”, the political cartoon that led to the coining of the term. The district depicted in the cartoon was created by Massachusetts legislature to favor the incumbent Democratic-Republican party candidates of Governor Elbridge Gerry over the Federalists in 1812. By Elkanah Tisdale (1771-1835) and originally published in the Boston Centinel, 1812.]

BulbgraphOnOffWhen assigning students an internet project, remind them they can refer to the “Internet Research Primer” tutorial for help.

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