Using OpenHistoricalMap with Sanborn maps from OldInsuranceMaps.net

OldInsuranceMaps.net provides web service endpoints that allow you to use georeferenced Sanborn maps as basemap sources while adding features to OpenHistoricalMap. For example, here’s a full mosaic of New Orleans, 1885, Vol. 2 in iD:

For other editions whose mosaics aren’t yet completed, you can still add any individual layer that has been georeferenced. For example, here’s Shreveport, 1896, Sheet 1 in iD

  1. Use the Items tab to find a map you want to digitize: oldinsurancemaps.net/search

  2. When you choose a map you’ll be brought to its overview page, which will look something like this:

  3. First check the Summary section: If a completed mosaic has been generated for this volume you will see this in the Download & Web Services section:

    • To open in OHM’s iD editor, just click the link!
    • To open in JOSM, you can copy the entire XYZ Tiles URL and use that.
  4. If there is no full mosaic for the volume, then you can head down to the Georeferenced section where you’ll see all of the individual sheets.

  5. Find a sheet you want to digitize features from and click its title, bringing you to its own overview page. You’ll find a similar Download & Web Services section as described above.

As you’ll quickly find: there is plenty of information here to map.

Happy mapping! Any difficulties or questions, just ask below :slight_smile:

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Excellent walk-through, thank you!

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Thanks for assembling this New Orleans map for the OHM community Adam. It is an incredible resource for its detail and accuracy. I hope it will encourage and inspire mappers to start adding data for this historic city. I’ve loved visiting New Orleans and have walked and marveled at its buildings while walking its various neighborhoods. Adding to the OHM map will be like revisiting these streets again and learning even more about their history.

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Adam, would you be willing to provide a recommendation, or an example, of how to tag features on this 1885 map using EDTF Start_Date and End_Dates without knowing the actual start and end date?

That way features like buildings can be mapped with the existing 1885 data for now, but specific or more accurate, start and end dates can be added later.

I’m actually a complete OHM beginner, so I would have to defer to @jeffmeyer and @Minh_Nguyen about this! Here’s a recent discussion that touches on the topic at least: On what date does end_date end?

It seems to me that when digitizing from maps like this, it would be really useful to have something like an “exists_on” date, because all you can often glean from the maps is that a feature existed at a certain point in time… Anyway, a good discussion topic for sure.

There are some examples of EDTF syntax on the wiki pages for start_date:edtf and end_date:edtf.

Some mappers have experimented with a key such as as_of_date, but you can express the same thing using start_date=1885 start_date:edtf=/1885 end_date=1885 end_date:edtf=1885/.

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That’s very helpful! I’ll be using that extensively. Thank you Minh.

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