The Geography & Map Division holds “A Kansas Atlas,” a seminal 1952 atlas published by the Kansas Industrial Development Commission with cartography by Dr. George F. Jenks. Any 21st century GIS user will immediately recognize Jenks’ name as the geographer behind the “Natural Breaks” or “Jenks Optimization” classification scheme widely used for breaking thematic quantitative data into classification schemes on maps. In Esri-based software, the “Natural Breaks (Jenks”) classification method, which maximizes variance between classification groups, is the default classification scheme for any graduated color map produced by the software. “A Kansas Atlas” is a remarkable work of thematic cartography that illustrates Jenks’ early approach to careful and thoughtful thematic cartographic design, published over a decade before he would go on to develop his ‘natural breaks’ classification scheme.
Upon first exploring the atlas, my immediate thought was that Jenks’ cartographic work in “A Kansas Atlas” looks remarkably modern. In his map designs, he experiments with graduated symbols and 3D visual effects. Both techniques are employed on “Persons Employed in Retail Trade – 1948,” which uses circles in graduated symbol sizes to show the number of retail workers per county, with an interior shading effect to make the circles look like they float and extend out of the map. 3D mapping was one of Jenks’ research interests, and he would go on to publish on the topic in 1966 with an article called “Three-Dimensional Map Construction,” co-authored by Dwight Brown, his colleague at the University of Kansas.
Jenks was a cartography student of Richard Edes Harrison while at Syracuse University. He eventually became a professor in the Geography Department at the University of Kansas, where he helped found and grow a cartography program beginning in 1949. As a geography professor with interests in thematic cartography during the era of geography’s “Quantitative Revolution,” Jenks turned his research interests to the science of thematic cartography. He was highly interested in cartography curriculums for students and the science of effective cartographic design. His work paid attention to the fine details of classifications schemes, error created by cartographers, generalizations of lines, colors and shading, and how a map reader’s eye moves across the map. In the above “Labor Force” map, Jenks again uses graduated symbols, this time with 3D boxes. Jenks’ cartographic work for the atlas used detailed statistical data. In this map, he is sourcing data from the Kansas State Labor Department’s Employment Security Division.
Elsewhere in the atlas, he also employs graduated line symbols, such as in the above “Commercial Traffic Flow” map. The weighted lines help create a sense of movement to show where within the state vehicles were traversing highways, and in what quantity. Interestingly, if you look at the classification scheme for the flow map, you will notice relatively round and clean classification breaks (100, 500, 1000, 1500). The dilemma of how to best break up data within a classification scheme from a scientific perspective became one of the organizing questions for his later work.
“Manufacturing Industry in Kansas” again uses graduated symbols, this time to express the number of manufacturing plants per county. Even more detail on the make-up of manufacturing industries is woven into the thematic design with the use of graduated pie charts. The map is able to visually summarize a very large amount of quantitative information in a way that makes it digestible for a map reader to understand. In a quick glance at the map, I can see that Garden City’s manufacturing was comprised of about half agricultural products, a much higher percentage of agricultural manufacturing than many of Kansas’ biggest cities at the time. This type of visual optimization for a map reader was exactly what Jenks was interested in.
“Wholesale Trade In Kansas” takes the pie chart symbology up a level. Each graduated circular symbol now shows two different types of information: the interior of the circle shows the proportion of county trade totals shared by the major cities in the county, while the outside ring of the circle shows (by proportion) the types of wholesale operations happening in the county. This type of practical, detailed business data would have been invaluable for organizations like the Kansas Industrial Development Commission, which published the atlas. It’s a great example of studied thematic cartography techniques applied to a specific and practical use-case.
Finally, “Population Changes 1940-1950” shows the increase (or decrease!) in residents per county between 1940 and 1950 through three line charts: rural change, urban change, and total change. A quick look at Crawford County, Kansas (the county second from the bottom in the southeast corner of the map) shows that the overall county population increased, but visualizing only the total change would have obscured rural population loss.
Jenks’ contributions to academic geography and cartography remain widely influential today, and today’s map-makers are likely to resonate with the visuals of the maps Jenks created. His contributions in formalizing higher education for cartographers and the science behind thematic cartography remain influential even for today’s cartographers-in-training.
To further explore the history of “A Kansas Atlas” and the work of Dr. Jenks, readers are encouraged to explore The George Jenks Map Collection at the Kenneth Spencer Research Library.