Meanwhile, Mark Gargul writes in response to Ken’s critique of his cartogram of the election results. Mark describes himself as an amateur and readily admits that other cartograms are “clearly more aesthetically pleasing. On the other hand, I was going for something different with my cartogram—specifically, to try to preserve riding-adjacency as much as possible.”

@kennethfield
… On the other hand, what I was going for was preserving, to the extent possible, riding adjacency. If Markham-Stouffville shared a border with Markham-Unionville on a real map, I wanted that border on the cartogram. Hence, the ugliness.

— Mark Gargul (@GargulMark) October 26, 2019

The other thing Mark was going for in his cartogram was to indicate the urban-rural split: metropolitan areas are given a black border: it’s easy to see which ridings are in Montreal or Toronto; seats that are partially urban and partially rural straddle those borders.

I'll summarize for you guys what I let Ken know in more detail: I wasn't going for pretty, but I was going for illustrating the rural-urban split, which doesn't come across well in the other cartograms or maps I have seen

— Mark Gargul (@GargulMark) October 26, 2019

So it’s doing several things at once that may not be immediately apparent.

Previously: A Cartogram of Canada’s Election Results; More Canadian Election Maps.

I’ve said it before: if you want to start a fight among cartographers, ask them what their favourite map projection is. Earlier this week I did just that: I felt mischievous and wanted to try out Twitter’s polling feature, so I ran a poll asking my Map Room followers what the best projection for world maps was. And because I was feeling particularly mischievous, I made sure to include both the often-reviled Mercator projection and its antithesis, the Peters projection, rounding out the list with two less controversial choices: the Winkel tripel projection used by National Geographic, and the brand-new Patterson projection announced late last year.

The results of the poll were utterly unexpected: 42 percent chose the Mercator projection.

Cartography fight! The best projection for world maps is:

— The Map Room (@maproomblog) November 25, 2015

I was trolling the Internet, pure and simple, and in the end I got trolled back. Fair enough.

Then again, maybe I wasn’t. The more I thought about it, the more I realized that, whether they knew it or not, the voters had a point. Because when you think about it, the Mercator projection has won in the cartographic arena that really matters today: online mapping.

Every online map service uses a variant of the Mercator projection called Web Mercator. Whatever its shortcomings—and there are many, owing to the fact that its calculations use a spherical Mercator model to save computational cycles—Web Mercator has become the de facto standard. And the size distortions at small scales that have made the Mercator projection the target of so much ire over the decades are simply moot for most use cases.

In many ways the past debates over the Mercator are moot: arguing over the right projection for wall-sized world maps—Mercator vs. Peters vs. Robinson—is fighting the last war. Mercator has become the default option for online mapmaking, simply because so many data visualization maps rely on Google Maps or OpenStreetMap for their base map layer. Other projections will be reserved for the professionals, people with access to more sophisticated mapmaking tools and the skill to use them, but for the most part, when data is mapped on the Internet, it’ll be mapped according to Mercator.

(For more on the controversy surrounding the Mercator projection, read Mark Monmonier’s Rhumb Lines and Map Wars: A Social History of the Mercator Projection. I reviewed the book in 2008.)