So You Want To Make A Map?

Maps are one of the oldest mediums for presenting data and storytelling. There’s a burgeoning increase in data and concurrent lowering of thresholds to access software to make maps of that data. But there’s still one vital component in the recipe to making a great map — cartography. Making maps has become the modern equivalent of the shift from typewriter pools to word processing. It’s become a self-service proposition for many, as part of their jobs or simply as a way to show something interesting to others.

Making maps has become the modern equivalent of the shift from typewriter pools to word processing.

But cartography isn’t innate in our ability to communicate graphically. There’s a language, a syntax, and a grammar. It takes a little knowledge and some practice to know what works and how to make a map work well to mediate the message to the reader. In this article, I’m going to go through some of the choices you’re presented with in designing a thematic map (a map of a theme of data) and how they can help or hinder how people interpret it. It’s worth remembering that most people have no idea about how to understand the way in which the map and the choices made in making it affect their perception of it. You design the map to avoid as many of these potential pitfalls as possible by being a smarter mapmaker.

So let’s get going, and map one of the UN Sustainable Development Goals — employed people below the international poverty line. The data arrives at my desk as a flat spreadsheet. There’s a latitude column and another for longitude that locates a point which is our starting location for making the map. And there’s a value for each record in the spreadsheet (each country) that is the data we’re interested in mapping.

Below is the data’s latitude and longitude points when plotted on a default background map.

Basic geocoded structure of the dataset

Each country gets one dot representing a spreadsheet entry of data on poverty at a national level. It’s really not very informative. Each dot is the same colour, size, and shape, and therefore, they look the same. Is poverty the same…