OldInsuranceMaps.net

A crowdsourcing site for creating and viewing georeferenced mosaics of historical fire insurance maps from the Library of Congress. See how it works or visit the about or FAQ pages to learn more.

Explore georeferenced maps from 237 locations...

Click a point to access maps of that locale, or search by place name.

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How it Works

Digital scans of Sanborn maps are available through the Library of Congress and are pulled into this site through the LOC JSON API , generating a "Volume Summary" page (Baton Rouge, 1885).

Contributors prepare each sheet in the volume, sometimes splitting it into multiple documents, each to be georeferenced individually (Baton Rouge, 1885, page 1).

Next, each document must be georeferenced by creating ground control points, linking features on the old map with latitude/longitude coordinates to create a geospatial layer (Baton Rouge, 1885, page 1, part 3).

As they are georeferenced, layers slowly build a collage of all the content from a given volume, and their overlapping margins must be trimmed to create a seamless mosaic.

Finally, all volume mosaics for a given locale are automatically aggregated into a simple web viewer so you can easily compare different years and current maps (Baton Rouge viewer).

Want to learn more? Visit the documentation site .

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OldInsuranceMaps.net is funded in part by the National Institutes of Health (National Institute on Aging: R01AG080401) through a partnership with University of Michigan Institute for Social Research, University of Richmond Digital Scholarship Lab, and the National Community Reinvestment Coalition. Read more in the ISR press release.

Many thanks also to our individual sponsors: Kevin H., Andrew M., Peter M., Pete Z., and Chris P.

To donate: paypal.me/oldinsurancemaps