Sanborn Fire Insurance Maps: seeing the exact building where your ancestors lived and worked.

What a Sanborn Map Shows About Your Ancestor’s Home

Founded in 1867 by surveyor D.A. Sanborn, the Sanborn Map Company drew large-scale (50 feet to an inch), color-coded maps of more than 12,000 American cities and towns so fire insurance underwriters could assess risk.

When we locate your ancestor’s street address on a Sanborn sheet from 1885, 1905, or 1922, the map reveals:

• The exact footprint and shape of the house, tenement, or shop on its lot, including front porches and backyard stables or workshops.
• Color-coded building materials: yellow for wood-frame houses, pink for brick, blue for stone, and olive for fireproof iron/concrete.
• The number of stories, roof material (slate, shingle, or tin), and whether the ground floor was a dwelling (“D”), a bakery, a saloon, or a grocery store (“S”).
• Both old and new street numbers whenever a city renumbered its streets—preventing researchers from photographing the wrong modern house!

Pairing Sanborn Maps With Annual City Directories

While federal censuses were taken only once every ten years, city directories were published every single year. By tracing a family through annual directories alongside Sanborn sheets, we can watch a newly arrived immigrant move from a shared boardinghouse to a rented flat, open a neighborhood shop, and buy a family home.