During the last third of the 19th century and much of the 20th, the Sanborn Company published maps used for fire insurance purposes. Few private subscribers used their services, but for insurance companies and municipal governments, Sanborn maps were essential to do business.
The Sanborn company sent its agents to cities across America or contracted with local workers to make accurate measured drawings of the densest parts of American cities. Sent back to their offices in Pelham, New York, the drawings were more accurately represented and then lithographed on 21 by 25 inch sheets. They included considerable amounts of information about each building, its occupants (especially if they represented a fire threat, such as hardware stores with flammable liquids or bakeries with coal- or wood-fired ovens), the heating system and other data useful for underwriting a fire insurance policy. To make the danger of fire more immediately apparent, the black-line maps were then watercolored by hand to represent the major construction materials: wood was yellow, brick was pink, stone, blue, etc.
You didn’t buy Sanborn maps. You subscribed to their service, so that maps could keep pace with the changing urban environment. New maps replaced the old. The rate of replacement obviously reflected the rate of growth and change. In Fargo, for example, a city I know much better because of its Sanborn coverage, there were maps for 1884, 1888, 1892, 1896, 1900, 1905, 1910, 1916, 1922 and 1929. Make a color photocopy of the same block in different years and you’ve made a virtual flip-book of change. That’s how accurate the initial measurements were.
Some time before the next exhibition, I intend to create a Sanborn page for Agincourt. Wish me luck.
PS: While these maps may be historically significant, especially to historians and preservationists, they can’t hold a candle to the artistic integrity of the 1888 Ludvig Simon map of Göteborg. Is it too late to consider a career change?