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Do Maps Have Morals? (18 May 2005)
Before taking his current job as a historian for the National Oceanic and Atmospheric Administration, Cloud spent more than a decade assembling an alternative genealogy of GIS, showing military planners, not idealistic landscape architects, to be its fathers. In the 1950s, the Defense Department recruited scientists to determine the exact distances between the earth's continents--essential for aiming intercontinental ballistic missiles. Later, Pentagon officials sent the first remote-sensing satellites aloft to photograph "denied territories" inside the Soviet Union. In the 1960s, the Pentagon converted those images into digital data, and in the 1980s, the U.S. Air Force launched the Global Positioning System, the essential tool for today's mapmakers.

These military projects were the pillars on which geographic information systems were built, Cloud says. In scale and sophistication, they dwarfed anything accomplished in the civilian world at that time. And the world imagined in these maps was not one of environmental sustainability but one of nuclear war.

As for Ian McHarg's transparent-overlay maps, intended to help preserve nature and facilitate more-livable cities--well, that, too, is a nice-sounding cover story, says Cloud. There were other forerunners of layered digital maps, he says, including some that were used for less uplifting purposes than McHarg's.

Searching through archives and old cartography publications, Cloud found several overlay maps from the 1930s and 1940s. They were, he says, "the most complex and accomplished uses of overlays yet found." One set, prepared by federal officials during the New Deal, depicted American cities and showed, with different translucent layers, data about problems such as high concentrations of decrepit buildings. Later maps, concealed for many years from public view, carried fateful red lines that enclosed blocks occupied mainly "by any distinct racial, national, or income group that would be considered an undesirable element if introduced into other parts of the city," in the words of a 1936 document cited by Cloud. Thus was born the term "redlining" (say, charging residents of targeted areas more for loans or insurance). Yet Cloud has found no evidence that others adopted these innovative mapmaking techniques and applied them more widely. Apparently, they were used and then abandoned.

While interviewing Lawrence Ayers, former deputy director of the U.S. Defense Mapping Agency, Cloud learned of another set of overlay maps that may have fallen on more-fertile ground. The maps were created by the German military during World War II and captured by American forces near the end of the war. They were composed of transparent sheets--sometimes 20 or more--showing such things as vegetation, soil, and road surfaces. According to Ayers, the Defense Department's own mapmakers quickly saw the value of this technique and adopted it themselves, first applying it to physical maps, then to digital sets of data. "The concept of the overlay is what the software writers picked up and used to take advantage of digital technology," says Ayers. "It goes back to the Germans."
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