Curious about the history of your parcel or maybe how downtown Healdsburg was laid out back in the day? The Sonoma County Library has a vast collection of historic maps including township maps, plat maps, Sanborn maps and historical atlases.

A complete set of Sanborn Insurance Company maps can be found at the library on microfilm. These maps were originally created to calculate fire insurance risks in a community. Lauded by historians and preservationists alike, they are a vital component in identifying what was located where in great detail.

Digital offerings at the Sonoma County Library also include portions of the “Historical Atlas Map of Sonoma County.”

A historical atlas is a collection of maps and artwork used to depict the geopolitical landscape and historical context of both a specific time period and location. They often include photographs, drawings and text to describe both what things looked and to some extent why.

Thos. H Thompson began publishing historical atlases of California counties in the 1870s. The “Historical Atlas Map of Sonoma County,” published in 1877, includes both beautifully drawn maps and illustrations of some of the local ranches. Much like a map, the drawings illustrate where things were located on specific property, including residences, roads and livestock.

For more information on the Sonoma County Library’s map collection, visit