Where there’s smoke, there’s fire; and where there’s fire, there’s insurance (at least since around the beginning of the eighteenth century). In 1866, Daniel Alfred Sanborn established the D. A. Sanborn National Diagram Bureau to provide maps of North American cities and towns to fire insurance companies. These maps used an elaborate system of color coding, symbols, and abbreviations to indicate a dizzying amount of information — from building materials to street widths; from locations of standpipes to the presence of flammable chemicals; from the height of a structure to the number of skylights. Sanborn’s company didn’t provide any insurance itself — it supplied the insurance companies with the information, in the form of maps, they would need to assess risk and assign premiums.
The most interesting piece of information that Sanborn’s mapmakers gathered was what each building was being used for. “S” meant store and “D” meant dwelling. But they didn’t stop there. The maps identify hotels, churches, breweries, stables, manufacturers of flint glass bottles, orphanages, launderers, cigar factories, chewing gum factories, jewelers, butchers, cobblers, drugstores, barbers, canneries, boarding houses, manufactories of artificial hair, dry goods wholesalers, cabinetmakers, photographers, window shade factories, and hundreds — possibly thousands — of other kinds of businesses. Later, they label roller rinks, movie theaters, garages. Even opium dens, gambling parlors, and brothels are dutifully marked down. In larger buildings, they might label the kitchen, the coal shed, where particular pieces of factory equipment can be found. They sometimes note whether a building has a nightwatchman. The maps are Whitmanian in their profusion of detail.
Detail of 1905 Sanborn map of Laredo, Texas, featuring City Hall, a “Mexican Theatre”, a building labelled ”Mexican Produce”, a “cock pit”, gambling den, bicycle mechanic, and other shops and services — Source.
Detail of 1916 Sanborn map of Butte, Montana, showing “Pleasant Alley” (later called “Venus Alley”), the red light district. “Female Boarding” (F. B.) was often used by Sanborn agents as a shorthand for brothels — Source.
Detail of 1899 Sanborn map of Tahlequah, Oklahoma, showing the Cherokee Male and Female Seminaries, tribal colleges that were among the first institutes of higher education to be established west of the Mississippi River — Source.
The Sanborn Map Company, as it came to be known, eventually used their system to map more than 12,000 North American towns and cities, covering almost every community with a population over 1000. To do so, the company sent out employees known as “striders” or “trotters”. One or more striders would set up shop in a town for a few months, sometimes renting office space. Following a hundred-page manual supplied by the company, they would sketch, measure, and chart every street and building in the territories they had been assigned. In 1917, during World War I, a Sanborn field surveyor was seen making drawings of the buildings in Fort Wayne, Indiana. Not knowing what the stranger was doing, several residents called the police, worried that he was a German spy. The anecdote paints a vivid picture of what these surveyors had to do. They had to observe. They had to ask questions, possibly intrusive ones. (Outhouses are occasionally discretely noted on Sanborn maps.) They listed illegal businesses (when they could find them) next to legal ones. Making a good map must have required some combination of nosiness, charm, officiousness, tact, and pushiness, depending on the situation.