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Old Insurance Maps – Georeferencing Sanborn Fire Insurance Maps on Modern Maps
I developed and maintain this site so I am both very happy to see it get posted here and also watching htop intently...

I wanted to point out it is a crowdsourcing project, so every overlaid page you see has been placed there by a person, often through large institutional efforts at universities, but also individuals just looking to learn about their hometown through these old maps. Thanks for the interest!

  • bduhan
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  • 57 minutes ago
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Great work! I started georeferencing old plat maps and aerial photographs from my area in QGIS and realized quickly it would be hard to ask other for help without a platform like this.

I’ll try running my own and see about importing existing work. Have you thought about extending the public site scope beyond insurance maps?

> Have you thought about extending the public site scope beyond insurance maps?

The maintainer is generalizing outside of Sanborn maps [0].

[0]: https://www.ohmg.dev/

Thanks for making this, I look at Sanborns all the time doing historic preservation-related work.

Is there a way to quickly search for a specific address or select a point and then see the relevant map? Larger cities have Sanborns covering many volumes, and I see I can use sliders to turn them on and off to find the relevant one, but I wanted to make sure I wasn't missing a quicker way of finding a specific address.

Great question: no. I've spent a lot more time making the georeferencing side of things work well than improving search and discovery, and even presentation (like the /viewer/ pages), of the maps on the site. It's something I hope to spend a lot more time on in the coming months. I know, dealing with those sliders is pretty cumbersome in big cities with many volumes (like SF).
Gotcha, no problem, just wanted to make sure I wasn't missing some obvious way. Still a super useful tool, thanks again.
  • dmd
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  • 2 hours ago
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Do you use IIIF for this? Do you know about https://allmaps.org/ ?
No (or, not yet...) and yes, I know the Allmaps team well--it is an excellent project. There are a lot of similarities, but I would say two high-level differences are 1) OIM is built around server-side processing that immediately produces downloadable files and web services (geotiffs) while Allmaps applies a client-side transformation to non-geo IIIF tiles, and 2) OIM is designed around the creation of mosaics from many different pages to a greater extent than Allmaps is. This year I do see bringing more IIIF/Allmaps tooling into OIM though, so stay tuned!
Hi Adam! Adam runs really fun events where you get to help him annotate the maps if you’re ever in the New Orleans area
Hi! I added a page about "georeference-a-thons" recently here: https://oldinsurancemaps.net/community-georeferencing/
Sanborn Fire Insurance maps document cities in extreme detail. Not only are the positions and shapes of buildings accurately mapped, but also rough outlines of the rooms, their construction materials, and even small details like if the building hired a night watchman. See downtown San Fracisco for example: https://oldinsurancemaps.net/viewer/san-francisco-ca/?sanbor...
Also a major plot point in Peng Shepherd's novel The Cartographers. Not a marvelous novel (though it's far better than anything I could write), but entertaining enough and an easy read.
They’re super fun to look at if you have live in an historic home.
Thanks for sharing. I went through a similar process recently, manually stitching together fire insurance maps from my hometown. A large part of the business district burned down in 1916, but maps from a couple of years earlier survived. It worked, but it was tedious. This would have saved a lot of time. Here's the link if anyone wants to check it out: https://fire.gorch.com/
Clicking on a lot of the maps gives me this ? I'm logged in as well

Unauthorized: You do not have access to this item.

Yes, there are a number of maps (the FHA ones and also one Sanborn) that are part of a research project that is still in the works, so they are hidden for now.