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Interpretation Points Used in Sanborn Maps

Using Sanborn Maps can be quite helpful in a variety of fields. From historical research to environmental engineers, the information contained in these maps can tell you a great deal with a certain area.

Maybe you are not familiar with the maps or how to interpret the information you see. Here are a few pointers to help you get started.

What Is A Sanborn Map?

A Sanborn map is a map that was constructed to show all the items in a certain area. They are documented over years of time to help people see how the landscape and area has changed. They originally helped fire insurance companies to know what liability the company has in an area. It would show items such as fire walls, property lines, addresses and locations of hydrants. They are helpful in all aspects of life helping to determine items such as historical significance and what materials the buildings were made out of.

Interpretation Points

Understanding the reason behind the map is only part of the equation. Each map has certain points that share information with you but you have to understand what you are seeing. Here are a few interpretation points and what they mean to you.


The scale of the map helps you to determine just how large of an area you are looking at. The Sanborn maps were drawn on a one inch to fifty feet scale. This was how the majority of the fire maps were drawn in the early days. This scale will be on the map so you can see what scale the particular map you are using shows.

Title Pages

These pages provide information that is historical and important to the maps you are looking at. This would provide information to the people in the town showing where the incorporated and unincorporated areas of a town were. It showed where the fire coverage was and what type of areas they covered. It shares with you today on how the areas changed and what was considered urban and rural areas.

Keys and Colors

Colors play a huge role in the Sanborn maps. Where you may not be used to seeing them on traditional maps, colors have a special importance on these maps. The color of the building dictates what type of material it was made out of. For example, an iron building would have a grey color or a brick building may have red. The key would tell you what you are looking at and you could quickly know what type of building you are dealing with. This helped firefighters to know the details of how a fire is going to move in a building they are approaching.

Symbols and Legends

When these maps were first created they were to convey insurance information. While they are used for much more today, they had to quickly get across information in a precise and fast manner. This is why the symbols and legends are so important. When you understand the distinct symbols used in the Sanborn maps, you can easily read the information you see before you.

As you can see these insurance maps is a great way to learn about the area you are researching or to see how they changed over time. These maps were quite critical in fire insurance companies and to those around the town. There are several interpretation points on the map and to understand the map, you need to understand those points. Make sure to check out what your particular map legends and key are so you can easily read the map and understand the data you have in front of you. These maps can help you to find environmental hazards or to determine the significance of a historical building. Be sure to thoroughly understand the map key to fully get all the information you are looking for.

The Sanborn maps online can truly get you a world of information about a particular area and the history surrounding it. Jen recommends checking these maps out to help you fully get the picture of how an area changed and progressed to what it is today.