When you think of the world, the Mercator projection is probably the map that comes to mind. It's everywhere: atlases, school walls, even Google Maps. It's also, very, very wrong, and it's been distorting our view of the world for centuries.
It's one of the most common projections used for world maps. Gerardus Mercator created it in 1569 to help with ship navigation. The map was revolutionary because it straightened both lines of latitude and longitude, which was great for sailors; all you had to do was draw a line to where you wanted to go on the map and follow your compass.
But to make a navigation-friendly map, the projection distorts landmasses the closer they are to the poles, giving us the wrong idea about the relative size of — and maybe even the importance of — some regions.
This creates what some mapmakers call "the Greenland Problem."
Greenland on Mercator's map is huge; it's bigger than the entire continent of South America. The same thing happens with Alaska. Using Mercator's projection, the state looks bigger than the entire country of Mexico. The farther land is from the equator on a Mercator map, the more stretched out it is. In reality, South America is eight times the size of Greenland, and Mexico is actually bigger than Alaska.
For the same reason, 2,000 miles on a Mercator map looks much different when it's measured near Central America versus when it's measured by Iceland. The fault is in the map.
This happens because mapmakers must rely on mathematical formulas to project the surface of the Earth, a sphere, onto the surface on a map, a plane. Calculus and complex algebra eventually improved map projections, yet the Mercator stubbornly remained a popular general world map.
Although it was a great navigation map, it was also used as a geographic map in classrooms and in atlases. The distorted view of Earth's landmasses in a Mercator's projection became how people saw the world.
Mapmakers and geographers weren't happy.
Everything started to change in the mid-20th century. There was a world war, and more airplanes were being used than ever before.
Editorials published in The New York Times in the '40s called for the Mercator to be discarded and reminded readers "the grossness of its errors should not be forgotten." In a series of orthographic maps in 1942 and '43, Fortune magazine declared the "Mercator is no map for global war" and that it was "a dangerous map to use in studying global strategy." A exposé on cartography published in Life magazine around the same time called the Mercator a "mental hazard in a war that is plotted on great circles across the land and sea and through the air."
Perhaps nowhere was the rejection of Mercator's projection more apparent than with Richard Edes Harrison's illustrations. The architect-turned-illustrator for Fortune magazine created maps truly fit for a world dominated by flight, offering revolutionary views of the planet as World War II raged. In Harrison's maps, it was clear just how obvious United States isolation was — or how many neighbors Europe had.
Maps were taking on a new use: persuasion.
Suddenly, maps became a convenient way to show just how threatening Germany's neighbor Czechoslovakia was (when it really wasn't) or how imperative it was to fight communism, or how threatening other countries were to the USSR. A transverse oblique homolographic map does wonders for showing how close, and how threatening, the USSR really was in this Times Atlas map.
Eventually, a German historian created what he said was a revolutionary map projection he marketed as the solution to the Mercator. For Arno Peters, the Mercator represented Western imperialism. His new projection, with a more prominent Africa and South America, was meant to emphasize what he called the "Third World." Reactions ranged from cautious amusement to outright hostility. Peters had trashed the cartographic community in writings promoting his map — and his version wasn't even original; a Scottish clergyman named James Gall created virtually the same thing in 1885.
Eventually, the American Congress on Surveying and Mapping stepped in and had a resolution. The organization and six other cartographic groups urged map publishers, the media and government agencies to stop using rectangular depictions like the Gall-Peters and Mercator for general purposes. The answer to Mercator's problem was not a new rectangular map, the resolution said, but instead non-rectangular projections like the Mollweide or Eckert IV.
The media picked up the resolution, including a column in The Washington Post. It even made it to the front page of The Wall Street Journal.
The Gall-Peters hasn't gone away. Boston Public Schools recently said it will now use the Gall-Peters in classrooms to "de-colonize" the curriculum. But it's not like the Gall-Peters is replacing all maps. You can find different types everywhere. The U.N. logo has an azimuthal projection, and a Goode homolosine is in the background of CBS' evening news broadcast. But if you're really worried about how to look at the world, you should probably just buy a globe.
If you're interested in more really cool maps, check out the two great collections we sampled for this video.
The first is the David Rumsey Map Collection, which has thousands of digitized versions. Mercator, Mollweide, Goode homolosine — this collection has it all.
Another great resource is Cornell University's PJ Mode Collection of persuasive maps, which has 800-plus digitized maps that were intended to influence beliefs.
A couple useful resources for figuring out the actual sizes of countries or continents include James Talmage and Damon Maneice's "The True Size Of ..." app. It lets you see how the Mercator projection distorts landmasses. The "MapFight" app compares the landmass of two geographic areas.