San Ardo’s post office opened in 1887
Most of San Ardo was built recently: 8% of its homes predate 1940 and the median home dates from 1963.
How San Ardo began
When was San Ardo founded?
The San Ardo post office opened in 1887, the earliest record of the town by name. Another post office, San Bernardo (1886), opened inside today’s town and later closed.
Lost post offices
San Ardo’s post office has been open since 1887. Another post office, San Bernardo, opened and closed inside today’s town.
US Post Offices dataset (Blevins & Helbock, CC0). Places and cemeteries from the USGS Geographic Names Information System (2021).
Questions about San Ardo’s history
What year was San Ardo founded?
The San Ardo post office opened in 1887, the earliest record of the town by name (U.S. post office records).
Memory lane
What the archives can’t tell you, neighbors can.
Where this page comes from
Founding dates: Wikidata, Wikipedia, the U.S. post office records of Blevins & Helbock (CC0) and the Census. Homes by year built: Census ACS 2020–24. National Register of Historic Places: National Park Service (list of May 22, 2026). Old photos, postcards and papers: Wikimedia Commons, the Library of Congress and other public archives, credited on each item’s page. Maps: U.S. Geological Survey historical topographic maps (via Esri) and Sanborn fire-insurance maps (Library of Congress). History text and census tables: Wikipedia (CC BY-SA 4.0). Places that used to be: USGS Geographic Names Information System (2021). How TownRatings grades history →
From the US Post Offices dataset (Blevins & Helbock) and the USGS Geographic Names Information System. Archive images are copied here with their credits and licenses, shown on each photo’s page. Refreshed monthly.