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Home » Cartography, Geographical Education, Geographical Thought, Geography in the Media, World

Uses and Misuses of the Mercator Projection

Submitted by on December 10, 2010 – 5:36 pm 8 Comments |  
The World Bank is not the only organization to misemploy the Mercator projection for basic world maps. In a Google image search of “world map,” roughly a third of the initial set of maps returned greatly inflate the high latitudes. Not all, however, grotesquely exaggerate Greenland; one particularly unsightly map, reproduced above, solves the problem by erasing the island. The most egregious misuse of the projection is perhaps found in television newscasts in the United States. Here Mercator’s world image seems to serve as an icon of global breadth, adding gravitas, if counterfeit, to the stories of the day. The image is so emblematic of respectability that a caricature version is employed by the satirical Daily Show. In the image above, a gargantuan Canadian archipelago crowns Jon Stewart. Note as well the attenuated and misshapen depiction of India, the slug-shaped Japan, and the numerous non-existent land bridges.

The Mercator projection was designed by its creator for shipboard use, the title of the original map telling us as much: Nova et aucta orbis terrae description ad usum navigantium emendate et accomodata (“new and improved description of the world amended and intended for the use of navigators”). Critical thinkers have long noted the absurdity of using Mercator projections for general purposes. In 1943, the New York Times opined that, “We cannot forever mislead children and even college students with grossly inaccurate pictures of the world.”* Yet mislead them we still do, although to a lesser extent than in the mid-twentieth century.

That is not to say, however, that the only appropriate uses of the projection are navigational. Google Maps, for example, employs Mercator’s perspective because it retains the correct shape of landmasses at any scale of resolution. (Or, as the Wikipedia puts it, “Despite its obvious scale variation at small scales, the projection is well-suited as an interactive world map that can be zoomed seamlessly to large-scale (local) maps, where there is relatively little distortion due to the projection’s near-conformality.”) As a result, Google Maps are quite serviceable for local or regional uses, but at the global scale they are worse then useless, depicting Ellesmere Island (population 146) in the Canadian arctic, for example as roughly the same size as Australia.

A considered defense of the Mercator projection is found in Andrew Taylor’s The World of Gerard Mercator: The Mapmaker Who Revolutionized Geography (2004, Walker & Company, New York). The book is well written and well researched, recommended to anyone interested in the history of cartography. Taylor’s vindication of his subject’s famous projection, however, is poorly considered. He embraces the Mercator projection for general purposes essentially because it is widely embraced: “It is Mercator’s map that appears on schoolroom walls, in diaries and magazines, and, most important of all, in peoples’ minds. That approval is the ultimate democracy” (p. 255). Such claims are extraordinarily anti-intellectual; if nonsense is widely held, we are told, it should be celebrated, as anything else would be an anti-democratic insult to the will of the people.

Epistemological populism, which equates truth with popularity, is a rare and extremist stance. It is difficult to imagine its claims being made so boldly in fields other than geography. When it comes to geography, however, lower standards often apply.

*The quotation is from Andrew Taylor’s book, referenced above.

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  • Asya Pereltsvaig

    Once again, linguistics may be another field where epistemological populism is quite pervasive. One good example of this is "the great Eskimo vocabulary hoax", as Geoffrey Pullum calls it: the widely-held and widely-popularized belief that the Eskimo language has a dozen/four dozen/100 (pick your favorite large number) of words for 'snow' (see http://itre.cis.upenn.edu/~myl/languagelog/archives/000405.html)

    Elsewhere he summarizes the problems with the current state of language/grammar education: "Try to imagine biological education being in a state where students are taught that whales are fish because that is judged easier for them to grasp; where teachers disapprove of tomatoes and teach that they are poisonous (and evidence about their nutritional value is dismissed as irrelevant); where educated people accuse biologists of "lowering standards" if they don't go along with popular beliefs. This is a rough analog of where English grammar finds itself today. The state of relations between the subject as taught by the public and the subject as understood by specialists is nothing short of disastrous…"

    Having taught language/grammar/linguistics at different levels and to different audiences, I find myself in agreement with Pullum on this…

  • James D

    Remember that Google Maps has a tool to draw a straight line. This usefulness of this is maximized by having straight lines be great circle segments; that is, by using the Mercator projection.

  • Alexis

    Straight lines on the Mercator are rhumb lines or lines of constant bearing, not great circles (unless you count the Equator). Only the Gnomonic projection displays all great circles as straight.

  • Martin W. Lewis

    Asya Pereltsvaig makes a good point — no doubt that I tend to overlook problems in fields other than geography. And James D. and Alexis for important information on mapping.

  • Jim Wilson

    A map is a form of symbolic communication and must always be decoded. Just because a town is represented as a dot does not mean it is at all circular in shape, and we all understand that. The mercator projection is certainly more useable for communication geographical information than the orange peel strips of chopped up globes that geography textbooks used to suggest in the 1970s. Until a more generally useful flat map comes along, therefore, I will continue to use Mercator projections, while pointing out that it distorts sizes, particularly near the poles. Of course, I don’t know anyone who spends any time thinking about polar issues who doesn’t already know that.

  • anon

    The daily show finally scrapped the Mercator projection!

    • Many thanks to anon for the Daily Show update. In regard Jim Wilson’s comment, I agree on the first point but disagree on the second. Many map projections are far better for general purposes than the Mercator. I prefer the compromise Robinson projection.

  • jorge

    The Latin title of the map should read “descriptio”, sans the ‘n’.