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Mercator Projection – Evil, or SuperEvil™?

April 22, 2010

Mapmakers take projections personally (see the Propaganda in Action section of this article for an example). Yes, they are simply methods used to represent our wonderful, slightly elliptical, Earth as a plane, but we mapmakers have to deal with them all the time. We wade through them, for hours on end. We bemoan the fact that hundreds of them exist and that no project ever has data based on only one of them (or even one datum for that matter, which is a slightly different issue).

So by now you may be wondering, “Why is the Mercator projection Evil?”

It comes down to distortion. The Mercator projection was created in the 1500s for navigation,

If only the distortion were at the equator...

and was great for sailors because any straight line on the map is a rhumb line, or a steady bearing from where you are to where you want to be. Sounds nice, right? But this projection distorts the world -a lot – especially around the poles. On the right is an approximation of what my picture would look like in the Mercator projection if I stood on Antarctica and my head went to Greenland. Note: I am not happy in said picture.

Why is the Mercator projection SuperEvil™?

For some reason (actually a number of reasons), the Mercator projection became the default projection used in classrooms around the world. So, for centuries we taught kids that Greenland was the size of Africa when, instead, it is the size of Algeria – not even the biggest country in Africa.

If that wasn’t bad enough, the Mercator became the projection for pretty much every web mapping service known to man. Thus, on Google Maps’ main page there is Greenland, staring right at you, looking all huge like it wants to fight. Russia looks pretty huge too (well, yes it is huge, but not thathuge) and people tend to think that the world actually looks this way, they do not notice that the scale bar changes in size in the same zoom view going from Alaska to Angola, and this distortion inevitably shapes how they view the importance of different countries are in the world. Also, it makes small scale web maps look just plain ugly.

What is better than the Mercator?

In order to change all this horrible, horrible distortion, some folks in the 60s decided that the Peters projection should be used for all world maps. Turns out the Peters’ projection was actually a ripoff of the Gall projection from over 100 years earlier (the Propaganda in Action section of the article referenced above has more info on this as well) and that a lot of these folks were tools. Personally I prefer the Winkel Tripel projection (seen at right) since it is much closer to what the world actually looks like.

ah, much better

The Winkel Tripel is a compromise projection, so distorts the world in a number of ways, but only slightly, as it has the smallest overall distortion of any projection. Also, National Geographic uses it and they have been my heroes since I was could walk.

Why change?

Some of the coming articles will show times when using the Mercator projection heavily distorts the message of a map. There is no doubt that in a number of places, the projection is used specifically for this purpose. But generally, misuse of the Mercator is a sign and symbol everywhere of mapping ignorance.  Its use is a sign that the mapmaker had little knowledge of the underlying geographic principles he or she was working with and that quite possibly, the remainder of the mapmaker’s analysis ignores similarly important principles.

So please, join me in abandoning this map projection for small scale maps. Leave it behind in the 16th century graveyard where it belongs.

5 Comments leave one →
  1. Joyce permalink
    April 22, 2010 9:22 am

    Your pic is an awesome example displaying the impact of Mercator distortion…yep, I remember teaching that stuff, but had no “real” way of bringing the idea home to kids.

  2. Nate permalink
    May 20, 2010 10:31 am

    I was always skeptical about greenland being such a beast up there. Score one for the skeptic.

  3. leurnid hand permalink
    April 1, 2011 11:09 pm

    The Dymaxion Projection (aka Fuller Projection) is an extremely low distortion map that avoids distorting the shapes of continents or countries, and maintains a uniform scale with a small margin of error.

    Both Mercator and Peters distort the relative size and shapes of land masses and make scaling distance off the map nearly impossible except on lines of latitude.

    While the Fuller Projection is far from perfect, it is one of the best projections for most scholarly work, but for one reason or another, it too has failed to catch on.

  4. September 15, 2011 3:36 pm

    “Its use is a sign that the mapmaker had little knowledge of the underlying geographic principles he or she was working with and that quite possibly, the remainder of the mapmaker’s analysis ignores similarly important principles.”

    As a mapmaker in NOAA’s Office of Coast Survey this is not true. We know what we’re doing when we make maps using Mercator projection. Our maps are for mariners.


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