Seeing people where they are
On the Mercator projection, boundary cases, and why 2024 should be the year of the population cartogram
2024 is a cartographically interesting year for two reasons: The Summer Olympics and the record-breaking number of people choosing elected leaders -- more than half of the world's population. For both reasons, this deserves to be the year of the cartogram.
■ Conventionally, we display maps according to physical shapes and political boundaries. When we do it with the entire globe, this tends to create substantial distortions that make places near the poles appear disproportionately large. (The Mercator projection is famously the most egregious violator, but even "good" projections still create distortions.)
■ But even when we find ways to mitigate the physical distortions, another huge distortion remains. When we illustrate political boundaries (around countries or individual states or provinces within countries), we end up prioritizing the margins. Margins, though, are just that -- edge cases.
■ The margin between Montana and Idaho is relatively recognizable, for example, but if we're representing people and what they do, it's not very important. What's important is to see where people are concentrated. Population clusters are important and density is important -- not the arbitrary boundaries drawn by things like rivers and longitudinal meridians.
■ Cartograms solve this by representing populations in equivalent units, then roughly placing them in proximity to one another. Thus, a cartogram of the United Kingdom represents London much larger than it appears on a geographical map -- because that's where all the people are. Similarly, a cartogram of the United States makes New England and the East Coast much bigger than Montana and Idaho, because that's where the population is weighted.
■ It's obvious how this makes election returns easier to process and understand, but it also makes global events like the Olympics more comprehensible. Land masses like Siberia don't win gold medals; the people who live in individual countries do. And what a lesson it would likely be for many people to realize that, contrary to most physical projections on the world map, countries like Nigeria and Indonesia and Pakistan are members of the top-ten club for population.
■ Even the finest, most balanced Winkel tripel projection showing their physical boundaries can't reveal how big they are in terms of human lives: The metric that should matter most. Given the scale and scope of events taking place this year, 2024 ought to be the year when cartograms make a splash onto television, computer, and smartphone screens everywhere.
