The Projection War: Mercator vs Gall-Peters and the search for fairness
The political and educational debate surrounding map projections. Why do Gall-Peters advocates accuse Mercator of Eurocentrism, and how does it affect schools?
A dispute about how to show the world
Maps look like pure mathematics, but the choice of projection can become a public matter. In the 1970s the German historian Arno Peters became a prominent opponent of the Mercator projection. He promoted an equal-area cylindrical projection, known today as the Gall-Peters projection, as a fairer picture of the world.
Peters argued that the Mercator map enlarges Europe and North America at the expense of Africa and South America, and so reinforces a view of the world seen from the wealthy North. The criticism was aimed mainly at world maps in schools and the media, not at navigation charts.
Which is larger in reality: Africa or Greenland?
Conformal or equal-area
The dispute was about two different properties of maps:
- Conformal projections, such as Mercator: keep angles and shapes in small areas, which is essential for navigation. The price is a very large enlargement of areas far from the Equator.
- Equal-area projections, such as Gall-Peters: keep the proportions of all areas. The price is distorted shapes. On the Gall-Peters map countries near the Equator are stretched vertically, while polar regions are flattened and stretched horizontally.
Cartographers also criticized Peters because his map was not new. The USGS album of map projections states that the same cylindrical equal-area projection, with standard parallels near 45°, was described in 1855 by James Gall of Edinburgh, and that Peters presented it in 1967. That is why it is now called the Gall-Peters projection.
What came out of it?
Both sides were partly right. The Mercator map is poorly suited to comparing the sizes of countries: in his USGS manual, John P. Snyder warned that when it is the main basis of the world maps students see, it leads to mistaken ideas. The Gall-Peters map, in turn, keeps areas at the cost of shapes that many people find unnatural.
Many publishers chose middle ground. The Robinson projection, designed in 1963 for the publisher Rand McNally, is neither conformal nor equal-area, but it limits both kinds of distortion. In 2018 came the Equal Earth projection, which keeps the proportions of areas and has shapes close to the Robinson map. We describe it in The Equal Earth projection. You can practice recognizing projections in the Name the projection quiz.