Choosing fonts

Choosing fonts should be about four primary things—legibility, readability, mood, and hierarchy. Legibility is paramount; no matter how fun that retro script font looks, if no one can read the labels, your map is useless, so use ornate fonts sparingly. Legibility also extends to individual letters—lowercase i, l, and j (as well as capital I and lowercase l) should be distinct, as should c and e. In a paragraph of text, these letters can often be assumed by context, but when used in isolated labels, particularly if the reader is unfamiliar with the subject area, context is not always present. 

Legibility is by and large about the shape of the letters themselves. As we learn to read, we develop the ability to recognize the silhouettes of letters, thereby speeding our ability to read whole words. Labels in proper case (first letter capitalized and all others in lowercase) are read more quickly than labels in all caps. Our eyes have to slow down and look more closely at the blockier capital letters, which can be an important way to emphasize certain labels, but exhausting to the reader if overused. For this same reason, many consider serif fonts easier to read, because the shapes of letters are more distinct, but if your labeling is not overly dense, sans-serif may be equally legible. 

Readability is more about the amount of whitespace in and around your labels. While this is often an issue more relevant for paragraphs of text, it can also apply to areas of dense labeling. A dense, heavy font means you will need to leave more space around each label to keep it readable, so if you've got a lot of labels to fit into an area, choose something lighter. And, if you do have blocks of text elsewhere on your map spread, you'll want those to coordinate with your map, so plan ahead.

Mood relates directly to the underlying psychology of fonts; there are some quick guidelines that can help us capture the right feel for our map. Typefaces with old style or transitional serifs convey dignity and a sense of tradition. Bold, slab serifs, and even modern serifs with considerable differences between the thick and thin strokes, convey power and strength. Sans-serif is often associated with precision, with the exception of some more frivolous fonts like the aforementioned Papyrus, Lithos, or Comic Sans. Fonts with irregular x-heights (for example, smaller vowels) can generate a certain amount of visual energy and excitement, but be careful not to compete with your actual map data. Scripts and italic forms of some of the old style fonts can imply elegance (think wedding invitations), but for mapmakers, they are typically used for water labels. It's often best to confine these to large bodies of water; a fancy script Pacific Ocean is going to be far more legible than a river in the same font.

In Chapter 3, Organizing the Page Structure, we discussed building an overall map hierarchy to lead your reader through the information in a logical way and help them prioritize important elements. Labels are an absolutely critical part of map hierarchy, and, because of their natural tendency to float to the top of the viewer's attention, can make or break the hierarchy of the entire map. Larger cities should have bolder and larger labels than smaller cities, although too much boldness can impair legibility, so use caution. In general, area labels should be softer, as their typically larger extent lends them more weight than usual. Important features should stand out from less important or contextual items. This can be done through the size and weight of an individual font, or through the use of an additional font.

This brings us to a discussion of what to do when labeling everything on the map in the same font isn't feasible; perhaps you have several sizes of cities, some landmarks, and a whole taxonomy of natural features, all in the same map. Compatibility of fonts is as important as the choice of fonts themselves. Font pairing, like wine and cheese, relies on contrast, but conflict can be jarring to the palette.