Map Readability in Crisis Situations

One thing that’s driving me a little crazy with COVID-19 news coverage is the use of colors on maps. Some maps are more useful than others, and if readers want to have a clear picture of what’s going on, a reader-friendly color scheme is critical to their understanding. Alas, some maps are less friendly than others.

Is That Turquoise or Aquamarine?

The first culprit I encountered was WFTV’s coronavirus case map of Florida:

Florida Blue

Image Credit:

While one can quibble about using blue as an intensity indicator, the color hues here are sufficiently close together that it can be difficult to discern which color/condition is being represented. Here’s another example, this time from the Washington Post:

WaPo Map

Original Caption: Location data firm Unacast identified places where residents are engaging in more social distancing in green — and less in orange. (Unacast) (Image Credit: Washington Post)

This map used at least three different colors of varying intensities. And while the caption indicates that they only used two colors–orange and green–at least one of those shades looks almost blue. And, again, the colors used are sufficiently close in value that it’s often difficult to read what’s going on state to state. Also, there is no scale or legend explaining the color values.

My brother-in-law noted that the map would be “really terrible for color-blind guys.” Heck, I’m not color blind and I had trouble seeing what the map was saying. I decided to shift the WaPo and Florida maps to black and white to see if their readability improved. Here’s where I ended up:

Image Credits: Washington Post (left) and WFTV (right); black and white coloring added by the author.

The U.S. map generated by the Post doesn’t do much better; however, the Florida map improved quite a bit by shifting to a range of a single color.

Sometimes mapmakers try to get their point across by including icons. Johns Hopkins University has been a go-to source for the news media here in the U.S. However, I’m not certain how effective their map is in depicting the virus outbreak:

Image Credit: Johns Hopkins University

To show intensity (number of virus cases), JHU uses circles of varying sizes. I’m not “sold” on that method of conveying intensity. Shape sizes are useful if you’re trying to compare physical area; they’re somewhat less helpful when comparing quantities. However, like the WFTV map, JHU does include a detail feature that pulls up additional information if you click on a particular location:

JHU Florida Detail

Image Credit: Johns Hopkins University

Okay, Smart Guy! What Would You Do Differently?

Here are some things that make maps more readable:

  • Use a single color with clear intensities to represent specific values.
  • If you’re going to use multiple colors, stick with two or three along the color spectrum so that readers can see obvious differences.
  • Include a legend explaining the colors! (Neither the U.S. nor Florida maps did this.)

The point of intensity maps is to call the reader’s attention to particular places in a given geographical area. Readers/media consumers are used to a value with “high intensity” being represented by a bolder, darker, or more eye-catching color than one with low intensity.

I also asked one of my graphic designer friends, Carrie, for her thoughts:

“Obviously avoid red and green since that’s the most common color combination that gives people trouble. I try and think in terms of contrast and not just color as well. Different organizations have color preferences. For example, I personally prefer to use blues, but when I worked for the Army, I had to use greens because blue is Air Force. There’s also emotional and symbolic attachments to color you have to be careful of depending on what you’re trying to present. Red is considered angry. Blues are calming. Green is earth-friendly. All that’s in the back of my mind as I’m designing something in addition to basic color theory.”

Is Anyone Doing Things Right?

There are good designs out there on the internet, too. Having griped about WFTV, I will now show an aspect of their map that I liked: the ability to click on a particular place and focus in on that location’s results:

FL Map Detail

I did note that up close, the color differences between counties are a little easier to discern. Also, both the WFTV and JHU maps include additional data around the map to give the reader a “global” view of the data. However, again, there is no “rating” system indicating how the colors are derived on the map–one presumes it’s by number of coronavirus cases.

There are also multi-colored maps that can still get the point across. This map created by Newsweek is probably my favorite because it incorporates a good use of color, intensity, and explanatory text.

Newsweek Corona Map

Image Credit: Newsweek

The bottom line here is that a wise use of color can help news readers/viewers get a clearer picture of what’s going on. A picture is worth a thousand words…unless those words are confusing; in which case the picture can make an already-uncertain situation worse.

About Bart Leahy

Freelance Technical Writer, Science Cheerleader Event & Membership Director, and an all-around nice guy. Here to help.
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1 Response to Map Readability in Crisis Situations

  1. Ooh. So pretty.

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