Most of these more common map types focus on a particular variable that is displayed. But what if you have multiple variables that you would like to present on a map at the same time?
Here is my attempt to collect examples of multivariate maps I’ve found and organize them into a loose categorization. Follow along, or dive into the references, to spur on your own investigations and inspirations!
Jim’s examples of maps that display more than one variable include 3D maps, multicolour choropleth maps, multiple small maps, and embedded charts and symbols. Useful and enlightening.
For Geographical magazine, cartogrammer extraordinaire Benjamin Hennig maps the geography of hate groups in America, with a set of cartograms that show where each category of hate group—anti-Muslim, anti-LGBT, neo-Nazi, neo-Confederate, and so forth—is located.
France held the first round of its presidential election this past Sunday. Unlike U.S. presidential elections, it’s by popular vote, with the top two vote-getters moving on to a second round in two weeks’ time.
The major candidates’ support was distributed unevenly around the country. Media organizations used several different methods to show this. The New York Times used a choropleth map, showing who among five candidates (including Lassalle, excluding Hamon, who finished fifth but does not appear to have won a commune: ouch) finished first on a commune-by-commune basis. Of course, when you have four candidates finishing within a few points of one another, when you win a district, you don’t necessarily win by much. The print edition of Le Figaro included choropleth maps detailing five candidates’ regional support as well.
Both the Times and Le Figaro use geographical maps, which can be misleading because of the number of votes concentrated in large cities, as Libération’s Julien Guillot points out. (This comes up in most countries’ elections, to be honest—certainly the ones where it’s the popular vote, rather than the constituency, that’s being looked at.) Slate uses a cartogram to compensate for that. (Both of these pages are in French.)
For those seeking local results rather than analysis, several French media organizations provide them through a very similar map interface: see, for example, the online results pages for France 24, Le Figaro and Le Monde. Each begins with a map of France: clicking on a département provides results for that département that includes a map showing each commune, which can also be clicked on. For some reason neither France 24 nor Le Monde show actual vote totals at the local level, which doesn’t seem sensible in an election by popular vote.
Finally, a couple of outliers. This page looks at the results from all presidential elections under the French Fifth Republic. And this page marks the 56 communes in which Marine Le Pen received not a single vote.
Oxford geography professor Danny Dorling spoke at the TEDx Exeter conference in April 2016. If you’re familiar with Dorling’s work, it will come as no surprise that he makes extensive use of cartograms to describe the world’s population. Video: TED, YouTube.
The second round re-vote of the Austrian presidential election took place yesterday. (The first round took place on 24 April; a repeat of the second round, narrowly won by Alexander Van der Bellen on 22 May, was ordered by the Constitutional Court.) Full, final results are not yet available, but austromorph.space has created the above cartogram of the preliminary results—showing, as you might expect, the strength of winning independent candidate Alexander Van der Bellen in the cities; support for the far-right FPÖ’s Norbert Hofer shrinks when you change from a map to a cartogram.
I’ve delayed posting maps of the 2016 U.S. presidential election results because—well, because like many of you I’m still recovering. But here we go. We’ll start with Benjamin Hennig’s cartogram of the results which, as cartograms tend to do, correct for the urban concentrations that made up Hillary Clinton’s vote, and demonstrate the rural nature of Donald Trump’s support. See it at Geographical magazine and Hennig’s website.
The white underlying geographic map places states in their familiar size, shape and location, allowing them to be identified quickly. Using a cluster of dots rather than a solid fill to represent the outcome ensures that the amount of red and blue on the map accurately reflects states’ weight in the election outcome, rather than the (irrelevant) surface area.
Like the tiled grid cartogram, the number of electoral votes in each state is easy to compare visually without counting or interpreting numbers printed on the map. Because each electoral vote is a discrete mark, it is possible to accurately represent the split electoral votes that are possible in Maine and Nebraska, or the possibility of a faithless elector.
The map may not look advanced today, but in 1883 it broke new ground by enabling Americans to visualize the spatial dynamics of political power. Readers responded enthusiastically. One reviewer pointed to the Republican counties in Arkansas—something left invisible on a map of the Electoral College returns—and wondered what other oddities of geography and history might be uncovered when election returns were more systematically measured. In other words, the map revealed spatial patterns and relationships that might otherwise remain hidden, or only known anecdotally. Perhaps its no coincidence that at the same time the two parties began to launch more coordinated, disciplined, nationwide campaigns, creating a system of two-party rule that we have lived with ever since.
(This map also inverts the modern colours for the two main U.S. political parties: here the Democrats are red and the Republicans are blue. Those colours were standardized only fairly recently.) [Geolounge]
For other ways of mapping election results, see this gallery of thematic maps, which includes things like 3D choropleth maps, dot density maps, and all kinds of variations on cartograms and choropleth maps. There’s more than one way to map an election. [Andy Woodruff]
The BBC’s election night map is bare-bones, showing which side won which local authority, but not by how much. Appropriate for the moment, and for finding your locality, but not necessarily very revealing.
But the EU referendum isn’t like a general election, where each electoral district has roughly the same population, and counts the the same in parliament. In this case it’s the raw vote numbers that count, and local districts can vary in size by as much as a couple of orders of magnitude. So the Guardian’s approach (at right), a hexagon grid that combines a choropleth map with a cartogram to show both the margin of victory and the size of the electorate, is probably most fit for purpose in this case.
I’m actively looking for other maps of the EU referendum results. Send me links, and I’ll update this post below.