GoKawiilOver the past few months I’ve been working on mapsnap, a program to automatically georeference old insurance maps. This post explains why these maps are interesting, how mapsnap works, and why this is worth doing.
I’m interested in history, cities, and maps, and in the United States that combination leads you very quickly to the Sanborn Insurance Maps. The Sanborn Map Company produced hundreds of thousands of detailed, block-by-block maps of every city in the United States from roughly 1870-1960. Their original goal was to help insurance assessment (Is this building made of brick or wood? Where are the water mains?) but today they’re valued for the unique view they provide into the history of urban spaces before the major urban renewal projects of the mid-20th century. You can read more about Sanborn maps at the Library of Congress, or watch this six-minute explainer video.
Here’s an example of one page from a Sanborn map (NY 1923 vol 1 p27):
You can zoom in to see more details:
There’s a lot of information here!
The color shows what material the building is made out of: red is brick, yellow is wood frame.
The numbers in front of each building (46, 48, 50, 52, etc.) are its address. This is a gold mine for sites like OldSF and OldNYC where you want to locate a photo using a historic address, which might not be the same as the current address.
Businesses in a building are labeled, e.g. the Bakery at 50 Oak Street or the Italian Marionette Theatre (sounds fun!). “S.D.” means “Store and Dwelling,” i.e. a store on the ground floor with residential units above.
The heights of the buildings are labeled. Reading right to left, there’s 50’, 40’, 40’, 40’, 44’, 66’.
As it turns out, the NYPL (and OldNYC) has a photo of this block! If you read the heights carefully, you can match them up to the buildings in the photo.
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