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Over the first few months of 2026, I’ve been expanding these city blocks of the 1885 New Orleans OHM map (shown below) to incorporate data from 1896, 1908 and 1951 Sanborn Maps.

It’s coming along rather slowly, but I’m getting better and more productive with this process as I tackle individual city blocks north of Canal Street.

First I have to prepare/correct/update the 1885 map:

Convert 1885 street addresses from buildings to separate 1885 address points (since the USPS made major changes to city addresses between 1885 and 1896)

Convert 1885 specific building names and functions to separate 1885 amenity points (so that buildings are more generic over time)

Correct building locations and wall positions to match contemporary 2026 locations where they are visible. Extend the building’s timeline if they are still currently standing.

Next, I extend the 1885 map to 1896 (the next new point in the Sanborn maps timeline):

Create new address points to match the 1896 map

Identify and extend any 1885 buildings that also appear on the 1896 map

Add any new buildings that were built between 1885 and 1896

Add 1896 business names and functions as 1896 amenity points

Extend the lifetime of other features (roads, rails, pipelines, etc)

Complete the city block so that the 1896 map is accurate

Repeat steps 1-6 to update the 1896 map to make a 1908 map

Repeat steps 1-6 to update the 1908 map to make a 1951 map

Sounds easy doesn’t it! It can get very complex. My biggest challenges are: 1) Dealing with positional errors, ie. reconciling old building locations and property lines to match today’s map. 2) Too much detail of small wooden buildings, awnings/porches or aux. structures. 3) Manipulating overlapping building geometry with different start and end dates (when buildings are modified over time).

This is a portion of the latest city block (along Decatur St.) that I’m working on to update from 1885 to 1896, 1908 and 1951. 

During 2024 and 2025, I spent many of my mornings sipping coffee and building out the 1885 Sanborn Fire Insurance Map in OHM. I created and tagged thousands of buildings across New Orleans. I also added as much information into OHM as I could, given the high level of detail available. Each building typically contains the following info:

Levels (number of floors)

Material (wood/brick/hard)

Street address (which were obsoleted in the 1890s)

Generic function (store/dwelling/stable/shed/lodging/etc)

Specific name or operator of a building or business

Start Date and End Date (I typically used /1885 and 1885/)

I spent about a year working on this project to create a digital version of this highly detailed 1885 Sanborn Fire Insurance Map (above) using OHM (OpenHistoricalMap.org). The digital OHM map, pictured below, has many ordinary buildings, is searchable and animated. You can see streets and buildings appear or disappear over time as you move the time slider.