BOTANY 211: Changed Landscape of Wisconsin (Spring 2022) : Sanborn Fire Insurance Maps

Sanborn Fire Insurance Maps are meticulously detailed, large-scale lithographed, color-keyed street maps created for all sizes of cities and villages. The maps are at a scale  of 50-feet to one-inch on 21" x 25" sheets of paper. Sanborn Maps helped insurance agents in the late 19th and early 20th centuries determine the degree of fire hazard associated with a particular property.

Today, we use these maps to help understand the look of a city block at points in history. These maps were made only for city and town blocks, not for rural areas. We can look at Sanborns to see how cities grow by noting when certain blocks start getting mapped, and we can watch the construction of buildings as each element was noted on these maps (for example - a new porch or brick vs. wood construction)

Pictured on the right is the "key"  sheet to the 1885 Sanborn map of Madison.  Note that Bascom Hill contains the entirety of the University of Wisconsin. Additionally the blocks between Gilman St and Lake St aren't even mapped, presumably because they weren't developed enough to warranted it. ​​

Compare the above with this 1908 Sanborn map. The many more colorful blocks on this key sheet indicate that there are more detailed maps for each of them. 

1908 Sanborn Showing Library Mall

The above image shows Library Mall as it was in 1908. You may see some things that are familiar and some that aren't. Try to think of three differences between this map and how you know Library Mall today, then click the link below to test your knowledge.

Knowledge Check Quiz