Matt Zhu

mapsDay 19 – Projections – Real Size: Alaska, Texas, California

Day 19 – Projections

Challenge Description: (GIS Day) Focus entirely on map projections. Choose an unusual or misunderstood projection to highlight a theme, or visualize distortion. (See xkcd.com/977)

My Submission

Quick Quiz: Which US state is the largest?

You probably know the answer is Alaska. In real life, Alaska is bigger than Texas and California combined.

But on many maps, Alaska looks way too big. Sometimes it looks like a massive continent the size of Brazil (check Google Maps now). Why?

The Problem: Earth is Round, Screens are Flat. Imagine trying to flatten an orange peel onto a table. You can’t do it without tearing it or stretching it. Mapmakers have the same problem. They have to choose between two things:

  1. True Size: Keep the area correct, but the shape looks squashed.

  2. True Shape: Keep the shape correct, but the size gets stretched.

For today’s map, I plotted the “Big Three” states side-by-side using different rules to show just how much the map changes.

Comparison of Alaska, Texas, and California across Albers, Mercator, and Mollweide projections

Click here to view high-quality PDF ⬆️

What am I looking at?

  1. Albers Equal Area (The Truth): This is the standard for government data. It prioritizes Size.

    • The Reality: Alaska is huge (2.5x bigger than Texas), but not a giant monster.

  2. Web Mercator (The Google Maps View): This is what we use for navigation. It prioritizes Angles (directions). To keep lines straight, it stretches everything near the North Pole.

    • The Distortion: Alaska is stretched to look 4x or 5x bigger than it actually is.

  3. Mollweide (The Global View): This is used for world maps. It keeps the Size right, but it squashes the Shape into an oval to fit the whole planet in one view.

References

Made by Matt Zhu for the #30DayMapChallenge.