How are maps made?

I get asked this question from time to time. The short answer is ‘on a computer’, but the people who ask me are curious about the full process, and deserve something better than that. So here’s a long answer:

1. Data must be collected

This can happen in many different ways. Here are a few examples:

Satellite imagery of the Lena River Delta in Siberia
Satellite imagery of the Lena River Delta in Siberia

Now that you have data (otherwise known as geographic information)…

2. Data must be processed

This work can take many forms, and can also be called GIS analysis:

Estimating solar power potential on rooftops
Estimating solar power potential on rooftops

3. Finally, the data must be presented and shared

Maps of tornado migration
Tornado Migration: Visualizing Big Data Movement

Historically, this entire process was called cartography. Today, most people in the GIS community are only referring to step #3 (presentation) when they use the word cartography. This is because the development of GIS technologies has allowed step #2 (analysis) to become far more powerful and prominent. We’re able to do things with geographic data today far beyond just drawing it on a map.

The next important question is Why make maps?

The answer: so we can make informed decisions. Decisions like:
Where should we focus efforts within a city to prevent homelessness?
What is the safest method to conduct a cave rescue?
How many sandbags do we need to prevent flooding?

Every day maps are made to support and communicate a vast range of decisions in the real world. Some are simple, some are complex, and almost all of them are made by combining the work of many different people. The Living Atlas is an ever-growing collection of curated data and maps provided by geographers all over the world, and is a great place to start making maps of your own.

And all of this is closely related to another big question: What is GIS?

About the author

Heather is a cartographer and artist. She creates resources for the tutorial gallery.


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