Three Rivers’ post office opened in 1879, and 1 of its places is on the National Register
More historic than 40% of U.S. towns. What drives it
Most of Three Rivers was built recently: 4% of its homes predate 1940 and the median home dates from 1980. Its Register listing is the Ash Mountain Entrance Sign.
How Three Rivers began
When was Three Rivers founded?
The Three Rivers post office opened in 1879, the earliest record of the town by name. Two smaller post offices, Kaweah (1879) and Hammond (1905), opened inside today’s town and later closed.
How historic is Three Rivers?
More historic than 40% of U.S. towns, on its age, its old homes and the National Register.
What drives Three Rivers’ History grade
On its age, its old homes and the National Register, Three Rivers is more historic than 40% of U.S. towns. Its National Register listings hold the grade up; its share of homes from before 1940 pulls it down.
Few California towns list much on the Register (a typical California town has 0.0 per 10,000 residents, the U.S. 2.4), so Three Rivers’ 4.4 sits above most of its state (86% of California towns have fewer) while its 1 listings outnumber those of 51% of U.S. towns.
Founding year: the first post office (other dates in Quick answers). Homes: Census ACS 2020–24. National Register: National Park Service, May 2026 list; each listing counted once (boundary changes and added documentation belong to their listing), and a historic district counts its contributing buildings. How TownRatings grades history →
1 historic place in Three Rivers
The country’s official list of buildings and places worth saving.
National Park Service, National Register of Historic Places. Photos from Wikimedia Commons, credited on each place’s page.
Lost post offices, old corners and burying grounds
Three Rivers’s post office has been open since 1879. Two other post offices 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 Three Rivers’ history
What year was Three Rivers founded?
The Three Rivers post office opened in 1879, the earliest record of the town by name (U.S. post office records).
How does Three Rivers rank for history?
Three Rivers is more historic than 40% of U.S. towns. The History grade combines the town’s founding era, the share of homes built before 1940 and its National Register listings. It’s a character grade, so it isn’t part of the overall grade. How it works.
What is on the National Register in Three Rivers?
One place: the Ash Mountain Entrance Sign (listed 1978).
How old are the homes in Three Rivers?
4% of Three Rivers’ homes were built before 1940 (Census estimate, ±3.4 points), against a typical 3.4% for a California town; the median home was built in 1980.
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).
From the National Register of Historic Places (1), 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.