Maps with a Message

As a geography professor at a large university and a former director of undergraduate studies in my department, I am accustomed to students sitting in my office wondering if they should major in geography. “But what use is a geography major? What job can I find with that?” they wonder. I then gently ask them if they have gone online or used their smartphone in the past five years. Their digital world is awash in maps. Smartphone apps show them how to get from place to place. Many of the web sites they visit are adorned with thematic maps—maps with a message if you will—that display a theme or topic spatially. Indeed, if students respond favorably to my pitch and major in geography, they will take courses in cartography or Geographical Information Systems (GIS) where they will learn to make thematic maps. If they have a knack for such things, finding a job post-graduation is typically not a problem. Corporations, urban planners, and environmental organizations all have a need to display their own messages through maps and allied images.

While thematic maps saturate our lives today, they are a relatively new invention in the history of cartography. In Mapping the Nation, Susan Schulten argues that such maps were largely invented and became commonplace in the nineteenth century. Thematic maps identified “spatial patterns and relationships” (p. 3) and were designed to open avenues of “inquiry, analysis, and interpretation” (p. 8). Schulten shows how historical and geographic knowledge were intertwined, perhaps even inseparable, in the early republic.

Schulten opens her book by showing how historians and others in the era sought to use thematic maps to better understand the nation’s past. Chief among them was Emma Willard, an early nineteenth-century teacher and author of one of the most popular history textbooks of the era, History of the United States, or The Republic of America (1828). Willard saw an intimate connection between geography and history and valued maps for “their ability to convey complexity, visualize the nation, and help students gain a more holistic view of the past” (p. 19). For her, maps were not just a way to convey the extent of territory or a tool for noting landmarks. They were also mnemonic devices that helped students and other readers memorize and understand key ideas in American history. In her historical atlas, Series of Maps (1828), she documented how territorial dimensions of eastern North America changed through time. But her spatial sensibility was not limited to maps in the conventional sense of a two-dimensional representation of a slice of territory. In her Atlas to Accompany a System of Universal History (1836), she sought to represent time through graphical terms in what were essentially illustrated timelines conveying events and processes in world history through lines of various widths. Visually, this historical map-timeline looks like a braided stream.

At the same time that Willard was writing books and making atlases to help Americans better understand their past, others were developing a deeper appreciation of old maps and the possibilities of historical cartography. One of the more notable among them was Johann Georg Kohl, a German immigrant trained in geography and passionate about the history of American exploration. He employed different colors to chart the routes of various explorers, and, later, the U.S. Coast Survey employed similar techniques to show the progress of the Union Army during the Civil War. Such maps sought to express change over time in a static two-dimensional medium. Perhaps the best example of how historians came to use thematic maps for historical purposes was the 1932 Atlas of the Historical Geography of the United States. This massive atlas had both facsimiles of historic maps and new maps displaying various facets of the nation’s past, such as agricultural regions, settlement patterns, transportation, and rates of travel. It displayed maps of particular subjects in a sequence, much like time-lapse photographs. The...