Introduction

Thematic maps are ubiquitous today. Think National Geographic. They are so common, in fact, that simple geographic maps have become rarities. (Think historic maps.) Their coming-of-age was the mid-1800s, after centuries of exploration and discovery, the rise of the Industrial Revolution and scientific inquiry, and technological improvements in printing. As will be seen, the instigators in the development of thematic maps were scientists, statisticians, and educators—not exclusively, as in the past, geographers, cartographers, or explorers.
            First, however, we need a definition. What am I talking about? What is a thematic map? A geographic map is a reference map of somewhere—Africa, for example. For my purposes, a thematic map is simply a map of something somewhere, such as the AIDS epidemic in Africa—something in some place. Hence, thematic maps add a Z dimension to an existing, or even fictional, X-Y (latitude-longitude) landscape. Topographic, or relief, maps might also fit under this wide umbrella, but they constitute such a large, self-contained set that they are not considered here. Most of these kinds of maps are issued in series—they are part of larger families—and, I would argue, are more about “dressing” space than interpreting it.

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