Map of the Month: Fire Insurance Plan slips and revisions
Is the image above some kind of Cubist cartographic experiment?* Did we lose all professional decorum and create collages from our maps? No, that's actually a behind-the-scenes glimpse at one of our most popular map genres: Fire Insurance Plans!
Fire Insurance Plans are detailed maps that show building footprints, uses, and materials from as far back as the 1880s. Because they provide snapshots of changing urban neighbourhoods, they also have an active afterlife as documents for historians, genealogists, urban planners, architects, and anyone else interested in the history of a site.
(For an example of how a Fire Insurance Plan can show changing buildings and shorelines, see our earlier blog post about Fire Insurance Plans!)
Once you start working with them, especially if you mainly consult scans, you may notice something odd:
See the faint lines around buildings, especially on the north side of King Street West? (This image is from the Toronto 1909 Fire Insurance Plan, Volume 1, Sheet 59.)
If you consult these materials in-person, you'll see that these lines are shadows cast by slips of paper that have been pasted onto the plan.
These are how Fire Insurance Plans were revised: the company would print sheets of these slips, representing buildings or properties that changed since the plan was printed. Recipients would need to hold the original unrevised plan, then cut out the slips, and glue them over places that changed.
For example, this sheet, showing Beamsville, Ontario, was printed in October 1921, then revised in April, 1928. Here's Sheet 1 of the original 1921 printing:
Here's what a sheet of these slips looks like:
These sheets number each of the slips, and note which sheet each slip should be applied to. Sometimes our slips came with notes tabulating how many slips should be applied to each sheet.
These revision slips are useful historical tools:
- Directly, they show updated information for the revised areas. Their presence also indicates that you are looking at a revised (not original) sheet.
- Indirectly, they suggest that unrevised areas likely did not change in the intervening time - or that the insurance company did not capture those changes. (E.g., unrevised areas likely stayed the same between 1921 and 1928 in the Beamsville example above.) As with any inference from absence, be cautious in applying this approach.
- Comparing unrevised and revised editions of the same Fire Insurance Plan sheet can reveal patterns of change.
Because Fire Insurance Plans are rare, we do not always have complete sets: in some cases, we only have the revised sheets but not the originals, while in other cases, we have only the slips themselves. While we would never cut sheets ourselves, sometimes they come to us with portions already cut:
Most researchers consulting Fire Insurance Plans never see the revision slips alone, so we hope that this post draws your attention to the presence of revisions, and offers a glimpse into the material lives of these maps.
All of the out of copyright fire insurance plans and atlases in the Map & Data Library collection can be consulted online:
Additional in-copyright fire insurance plans can be consulted in person at the Map & Data Library, contact us for details.
* Are you interested in avant-garde cartographic art? If so, we suggest a short Surrealist film from 1980, meant to accompany a Parisian exhibition on cartography.