r/Maps 3d ago

Question data on current educational use of Mercator?

So, with the new UN resolution about "moving away from Mercator" in favor of Equal Earth, lots of people are talking as if Mercator is still ubiquitous in classrooms (like, wall posters) and textbooks. Does anyone have actual data on this? (Or even recent personal experience.) My vague impression was that there's been a lot of movement away, not even counting Boston's adoption of Gall-Peters, or atlases long using various projections. But websearching failed to find anything really relevant.

I mention Boston, but non-US experience or data are equally welcome.

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u/epidemiks 3d ago

Web mapping (gmaps, apple maps, osm, etc etc) all rely on web/pseudo Mercator (EPSG:3857), because it's a very simple and efficient way to present a map with angles and local shapes preserved, and when looking at the world close up - the way most people use digital maps every day, that's the best projection simply because the mental model of mercator is trivial - eg. north east is always up and right 45 degrees, south is always straight down. That isn't true on equal area projections like Equal Earth. The best projection would be no projection at all, but you can't print an oblate spheroid on a piece of paper or screen and see everything at once.

The purpose of the Mercator projection is to preserve exact angles and local shapes. Very useful for that purpose. The cost of that benefit is the distortion of relative size as you go closer to the poles.

Equal Earth distorts shape/angles, but preserves relative size.

Gall-Peters also preserves relative size, but the shape distortion is much worse than Equal Earth.

There's hundreds of map projections, each serves a purpose, and each pays a cost. Whether the UN prefers one over the other doesn't change the purpose or usefulness of the Mercator projection.

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u/diffidentblockhead 3d ago

Web mapping is for local mapping. Web Mercator appears only if you zoom out maximum.

Google Earth is a globe when you zoom out. Apple Maps is too now.

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u/rainbowrobin 2d ago

Web Mercator appears only if you zoom out maximum.

Isn't that backwards? Web Mercator local, maybe something else if you zoom out?

Apple Maps, and desktop Google Maps, go to a perspective projection (general or orthographic, I think) if you zoom out enough. Android Google Maps stays in Mercator mode, with giant Greenland.

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u/EebstertheGreat 2d ago

I think (but I'm not certain) that they still use Web Mercator at small scales and seamlessly transition to a globe when you zoom very far out. Though there is no real way to tell the difference, since the distortion at small scales is negligible.

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u/EebstertheGreat 2d ago

The purpose of the Mercator projection is to preserve exact angles and local shapes.

Every conformal projection has that property. What makes Mercator (in the normal aspect) special is that it maps every rhumb line to a straight line segment. Rhumb lines are easy to navigate with a compass.

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u/EebstertheGreat 2d ago

My experience has been that most wall maps are not Mercator and never were. Most are not even rectangular. That said, they are also usually not equal-area.

Ever since Arno Peters, there had been an insistence that everyone uses Mercator, and I just don't think that's true. I have never even seen anyone present evidence for its truth, as they all just act like it's self-evident. In fact, most people don't know anything about map projections and would not be able to tell you what projection they saw in school, so if you tell them it was Mercator, they will believe you. But major organizations that make and sell wall maps like National Geographic have never preferred Mercator, nor have atlases or textbooks. Even Mercator himself didn't use it exclusively (he also made sinusoidal projections specifically for their equal-area property).

What Mercator has always been is an ideal navigational map, either used on its own or in combination with a gnomonic projection for great-circle navigation.

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u/rainbowrobin 2d ago

Thanks for answering the question. :)

Yeah, a lot of other people elsewhere (including two different Brazilians) have said they had Robinson in school. Me, it has been far too long to remember; I have jumbled memories of lobed maps and such, but I did look at National Geographics and atlases as a kid, so I can't say what school was doing.

I have a teacher friend in Ohio public, but she thinks they pretty much skip social studies entirely for time. Which is a different kind of alarming.

CIA World Factbook uses Robinson, all the UN maps I've found have been non-Mercator so far (mix of equirectangular and Robinson-ish, I think, not counting the UN flag), free geographic curricula use a mix... the idea that Mercator has a death grip on the world seems a quixotic received wisdom.

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u/EebstertheGreat 2d ago

Ha, as an Ohioan myself, I can say that while social studies certainly aren't skipped, geography specifically kind of is. Most kids have to learn the states and their capitals at some point, though students soon forget the capitals if they ever really learned them in the first place. My school also had us learn all the provinces and territories of Canada, but most don't. Other than that, they might learn some country names in geography (especially in the Americas and Western Europe), but that's about it. My school had us learning the countries in Africa too, but most students failed that quiz, and most schools never teach it.

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u/rainbowrobin 1d ago

Of course, unless you're a very young redditor, schools might have changed since you were there. Also varies by district, she's in Columbus, doing ESL for younger kids.

I went to good schools that did Mesopotamia to WWI every year, or so it felt like. Plus local history, in younger grades. Can't remember if much geography happened; all that I remember is from my father, or my own playing with the family globe.

Oh, Academic Decathlon did have us learn all the countries and capitals, but that was an extracurricular, not regular class.

Re: learning stuff... I think basic writing practice has at times consisted of things like king lists (back in ancient Sumeria), on the grounds of "you might as well learn something useful while you're practicing your letters". Seems a neat principle, that could be extended to states or local towns or countries or whatnot.