Mapping the Transcontinental Route for United Air Lines

Hal Shelton’s natural-color maps of the United States gave air travelers a whole new way to see the country.

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Jobs were scarce when Hal Shelton graduated from California’s Pomona College in 1938 with a degree in scientific illustration. So he took a position as “rod man” with a U.S. Geological Survey topography team, setting up survey instruments and making detailed drawings of various sites. Shelton didn’t stay with the USGS long, just a year, eventually taking a teaching job in the San Diego school district.

During World War II he returned to the USGS, this time as a topographic engineer mapping Nevada’s Jarbidge Mountains. When Shelton asked the local residents to name the peaks of the nearby ranges, he found they couldn’t understand the contour maps produced by the USGS, which were extremely specialized. “The USGS manual at that time,” notes Tom Patterson and Nathaniel Vaughn Kelso, “specified using a green tint for vegetation only for areas where you could hide a small detachment of troops or nine mules.”

The experience in Nevada would transform Shelton’s thinking about cartography. It convinced him that conventional topographic maps did not depict the landscape in a way that was helpful to the general population. While on temporary duty with the Air Force, he was asked to update an aeronautical map of the Sahara, and decided to experiment with natural colors. The old map had used conventional symbology—“a dense network of blue lines portrayed intermittent wadis [dry channels], and a green tint filled lowland areas all but devoid of vegetation,” according to Patterson and Kelso. (The blue lines, said Shelton, “would tempt a pilot to land and go trout fishing.”) Shelton recolored the chart to make dry areas look appropriately arid, the way it would be seen by a pilot flying overhead.

Shelton’s experimental maps caught the eye of aviation pioneer Elrey Borge Jeppesen, whose company published aeronautical manuals and charts for pilots. Jeppesen thought Shelton’s cartography technique “ideally suited for airline passengers,” writes Susan Schulten in A History of America in 100 Maps (University of Chicago Press, 2018). “Together they collaborated on a series of innovative charts for United Air Lines.” (See a larger version of the above map here.) Shelton was paid by the square inch, notes Patterson and Kelso, and each inch could take between one hour to one day to complete.

“He deemphasized boundaries, cities, and roads,” writes Schulten, “minimizing the human presence on the land in order to present the earth below as it might be apprehended—or even imagined—from higher elevations.” Shelton used hundreds of aerial color photographs, as well as data on climate, rainfall, landforms, and drainage, “then began etching and painting the charts—inch by inch—through a secret process.”

Shelton’s maps were so realistic, writes Schulten, that long before satellite imagery, NASA used Shelton’s work to identify photographs of the earth taken on early space missions.

Map posted with the permission of the University of Chicago Press.

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