Using Sanborn Maps for Genealogy & Local History

If you've ever looked at a family photograph from the early 1900s and wondered what the neighborhood around it looked like — what businesses were on the corner, whether the house next door was made of wood or brick, how wide the street was — Sanborn maps can answer those questions with remarkable precision. These maps are one of the most underused resources in genealogy, offering a level of physical detail that census records, city directories, and photographs simply cannot match.

What Sanborn Maps Reveal for Family Historians

For genealogists, Sanborn maps provide something uniquely valuable: a ground-level view of the physical world your ancestors inhabited. With a street address from a census record or city directory, you can locate the exact building on a Sanborn map and learn:

• The building itself — Was it a single-family home or a multi-unit flat? How many stories tall? Was it made of wood frame or brick? Did it have a basement?
• The neighborhood — What surrounded your ancestor's home? Were there factories nearby? A church on the corner? A saloon down the block? A school within walking distance?
• The workplace — If your ancestor worked in a factory, mill, or shop, Sanborn maps often show the exact building, including details about what was manufactured there and how the building was constructed.
• Changes over time — By comparing Sanborn maps from different decades, you can see how a neighborhood evolved during the years your family lived there — new construction, demolitions, changes in building use, and the arrival of infrastructure like water mains.

Decatur, Illinois (1915)East Saint Louis, Illinois (1905)Buffalo, New York (1889)

A Step-by-Step Research Process

Here's how to use Sanborn maps effectively in your genealogy research:

Step 1: Establish an Address

Before you can use a Sanborn map, you need a specific street address for your ancestor. Good sources for historical addresses include:

• U.S. Census records (1880 and later often include street addresses in urban areas)
• City directories (annual publications listing residents and businesses by address)
• Vital records (birth, marriage, and death certificates sometimes include addresses)
• Naturalization records (often include a home address)
• Draft registration cards (WWI and WWII cards include home and work addresses)

Step 2: Find the Right Sanborn Map

Once you have an address, look for a Sanborn map of that city from approximately the same time period. Remember that Sanborn mapped most cities multiple times, so try to find the edition closest to the date you're researching. Key resources for finding maps include:

• Library of Congress — The largest collection, with many maps digitized and freely accessible online
• ProQuest Digital Sanborn Maps — Available through many public and university libraries
• State and local libraries — Many hold Sanborn maps for their region
• FamilySearch — The LDS Church's genealogy platform includes some digitized Sanborn maps

Step 3: Navigate to Your Address

Sanborn maps cover cities in sections, with each sheet showing a few blocks. Use the title page's index map to identify which sheet number covers your ancestor's street. Then find the specific address on that sheet. Street numbers are typically printed along building frontages.

Step 4: Read the Map

Once you've found the building, use the color codes, symbols, and abbreviations to learn everything the map reveals about it. Note the construction material, number of stories, building use, and any special features.

Step 5: Expand Your View

Don't stop at the building itself. Look at the surrounding blocks. What was the character of the neighborhood? Was it primarily residential or mixed-use? Were there industrial facilities nearby? What churches, schools, or public buildings were within walking distance?

Pairing Sanborn Maps with Other Records

Sanborn maps become even more powerful when combined with other genealogical sources:

• Census records + Sanborn maps — The census tells you who lived at an address; the Sanborn map shows you what the building and neighborhood looked like.
• City directories + Sanborn maps — Directories reveal which businesses operated at a location; Sanborn maps show the physical building and what surrounded it.
• Newspaper archives + Sanborn maps — If you find a news article about a fire, accident, or event at a specific address, the Sanborn map lets you visualize the scene.
• Historic photographs + Sanborn maps — Photos show what buildings looked like from the outside; Sanborn maps reveal their construction, layout, and surroundings from above.

Common Discoveries

Genealogists using Sanborn maps frequently uncover surprising details about their ancestors' lives:

• A family listed as living at a “dwelling” in the census might turn out to have lived above a store their family operated
• An ancestor who worked in a “factory” might be located in a specific planing mill, ironworks, or textile operation
• A neighborhood described in family lore as “nice” or “rough” can be verified by the types of buildings and businesses that surrounded the family home
• Buildings that still stand today can be confirmed on Sanborn maps, connecting present-day structures to family history

The Title Pages as Historical Context

While the detailed interior sheets are most useful for address-level research, the title pages in our archive offer valuable context for genealogists. Each title page typically includes population figures, information about the city's water supply and fire department, and a small overview map showing the extent of the surveyed area. These details help paint a picture of the city your ancestors knew.