Gall–Peters projection
An equal-area map projection at the center of political controversy.
The Gall–Peters projection is a rectangular, equal-area map. Because it preserves area, it heavily distorts the shapes of most landmasses, a trait shared by all equal-area projections. This cylindrical projection has two lines of zero distortion at 45° north and 45° south. Its name honors both James Gall and Arno Peters. The map became famous in the late 1900s as the focus of a debate over the political messages embedded in cartographic design.
James Gall, a Scottish clergyman, first described this projection in 1855 during a meeting of the British Association for the Advancement of Science in Glasgow. He called it "orthographic" and formally published his findings in 1885 in the *Scottish Geographical Magazine*. Arno Peters later popularized the projection starting in the early 1970s with his "Peters World Map." The combined name "Gall–Peters projection" first appeared in a 1986 pamphlet by the American Cartographic Association, written by Arthur H. Robinson.
The projection's formula maps a sphere onto a vertical cylinder. The sphere’s longitude (in radians) becomes the x-coordinate, while the y-coordinate equals twice the globe’s radius times the sine of the latitude. This doubling of the cylinder’s height—a stretch factor of 2—is what sets the Gall–Peters apart from other cylindrical equal-area projections. Those projections differ only in the ratio of their vertical to horizontal axes, which determines their standard parallels (the lines of no distortion). For the Gall–Peters, those parallels are 45° north and south. Several other named versions of the cylindrical equal-area projection exist.
- type
- Map projection
- inventors
- James Gall and Arno Peters
- standard_parallels
- 45° N and 45° S
- property
- Equal-area
- also_known_as
- Peters projection, Gall orthographic
Lore & Background
The Gall–Peters projection is a rectangular, equal-area map projection. As with all equal-area projections, it significantly distorts the shapes of landmasses. It is a cylindrical equal-area projection, and the regions along latitudes 45° north and south are the only areas on the map that are free from distortion. The projection was first described in 1855 by the Scottish clergyman James Gall, who presented it at a science convention and later published a paper on it in 1885. He named it the "orthographic" projection. The projection initially passed unnoticed. In the early 1970s, German filmmaker Arno Peters independently devised a similar projection and brought it to a wider audience through his "Peters World Map". Peters’s original description contained a geometric error that, taken literally, implies standard parallels of 46°02′ N/S, but the text made clear he intended 45° N/S, making his projection identical to Gall's. The name "Gall–Peters projection" was first used by Arthur H. Robinson in a 1986 pamphlet by the American Cartographic Association. The projection became the centerpiece of a late 20th-century controversy about the political implications of map design, as Peters promoted it as a superior alternative to the Mercator projection, which he criticized for making Europe and North America appear disproportionately large relative to Africa and South America.
Reader's Guide
The Gall–Peters projection became a focal point of controversy in the late 20th century due to its political implications. Arno Peters promoted it as a superior alternative to the Mercator projection, arguing that Mercator greatly distorts the relative sizes of regions, causing wealthy Europe and North America to appear very large relative to poorer Africa and South America. These arguments swayed many socially concerned groups, including the National Council of Churches and the magazine New Internationalist. Peters bolstered his campaign with inaccurate claims that the Gall–Peters projection was the only 'area-correct' map, that it possessed 'absolute angle conformality', had 'no extreme distortions of form', and was 'totally distance-factual'. The cartographic community reacted with hostility to Peters's criticisms, which framed the profession as clinging to outdated, Eurocentric precepts. The name 'Gall–Peters projection' was first used by Arthur H. In recent years, 'Gall–Peters' seems to dominate usage.
Did You Know?
- The projection has standard parallels at 45° north and south, where there is no distortion.
- Peters inaccurately claimed the projection was the only 'area-correct' map and had 'absolute angle conformality'.
Frequently Asked Questions
What are Gall–Peters projection's powers and role?
Its signature ability is equal-area: every country or territory occupies the correct proportional footprint on the page. The only places where shapes come out perfectly undistorted are along the 45° north and 45° south standard parallels.
How does Gall–Peters projection's story end?
There is no tidy final chapter; instead, its legacy is a late-20th-century controversy that never fully settled. It remains a polarizing figure in cartography, championed by those who see it as a corrective to Eurocentric maps and criticized by those who find its shape distortions unacceptable.
Why is Gall–Peters projection important?
It turned a technical design choice into a public political argument, forcing people to confront the idea that picking one projection over another can make continents look bigger or smaller than they really are. That debate broadened the conversation about neutrality in visual representation far beyond the map-making community.
What are Gall–Peters projection's known weaknesses?
As with every equal-area projection, it warps the outlines of most landmasses, and the effect is most dramatic for regions far from the equator. This makes it visually striking but less practical for tasks that rely on true shape, such as navigation or comparative geography.
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