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CHistory
History · Thermalito

Thermalito’s post office opened in 1895, and 13% of its homes were built before 1940

More historic than 33% of U.S. towns · #306 of 847 in California. What drives it

Below: maps from 1912 on and the census since 1970.

1895first post office
0on the National Register
13%homes built before 1940
Add an old photoShare a memory
Quick answers

How Thermalito began

When was Thermalito founded?

1895

The Thermalito post office opened in 1895, the earliest record of the town by name.

First census: 4,217 in 19702020 census: 7,198131 years

How historic is Thermalito?

C

More historic than 33% of U.S. towns, on its age, its old homes and the National Register.

What drives the grade ↓
Founding year: the first Thermalito post office (Blevins & Helbock, CC0).
History grade

What drives Thermalito’s History grade

On its age, its old homes and the National Register, Thermalito is more historic than 33% of U.S. towns, #306 of 847 in California. Its share of homes from before 1940 holds the grade up; its National Register listings pull it down.

C
HistoryA character grade: shown, never part of Thermalito’s overall grade.
Founding era1895, from the first post office: founded 1850–1899, an older era than 37% of U.S. townsC+Homes built before 194012.6% of homes (±7.1) · typical CA town 3.4% · U.S. 8.4%B−National RegisterNo listings counted · typical CA town 0.0 per 10,000 · U.S. 2.4C
All U.S. towns we grade (21,289)Ahead of 33%
NewerOlder
California towns of 2,500+ (847)Ahead of 64%

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 Thermalito’s 0.0 sits below most of its state (31% of California towns have fewer) while its 0 listings outnumber those of 23% of U.S. towns.

How sure. Graded on any two of the three inputs instead, the letter would range from C− to C+. The pre-1940 share is a Census survey estimate (±7.1 points). The founding year is the first post office, not a stated founding date.

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 →

What stands out about Thermalito’s past

Read from the archive, the National Register and the record. The page puts what stands out first.

A history waiting to be writtenNo old photos of Thermalito are in the public archives yet. The rest are in attics and albums.On the map since 19123 editions of the USGS map, 1912 to 1970. Watch Thermalito change.
★ What stands out · Help out

Start Thermalito’s collection

The first neighbors to add old photos shape how Thermalito’s history is told.

Decades since 1900 with photos
00s10s20s30s40s50s60s70s80s90s
0 of 10 decades. The empty ones are waiting for someone’s album.
Share a family photoSign in to add one+10
On the map

Thermalito on the map, 1912 to 1970

Every edition of the U.S. Geological Survey’s map of Thermalito. Tap a year, or press play to watch the town change.

Thermalito on the 1912 USGS mapThermalito on the 1947 USGS mapThermalito on the 1970 USGS map1912Oroville sheet · 1:31,680

U.S. Geological Survey historical topographic maps (public domain), via Esri’s collection of the scans. The red ring marks the center of Thermalito.

The story so far

Thermalito, in brief

Wikipedia doesn’t have a history of Thermalito yet. The photos, dates and memories neighbors add here are how it gets written.

Thermalito (Spanish for "Small Thermal") is a census-designated place (CDP) in Butte County, California, United States. The population was 7,198 at the 2020 census, up from 6,646 at the 2010 census. The area is generally considered an integral part of Oroville, and borders the town on two sides, in addition to the near-enclave of the city of Oroville surrounded by Thermalito on all sides, with the exception of the extremely narrow spit of land connecting Afterbay to Oroville proper.

Its first post office opened in 1895. Between the 2010 and 2020 censuses its population grew from 6,646 to 7,198 (+8%).

Intro from Wikipedia. Population: U.S. Census Bureau.

Timeline

Thermalito, 1895 to 1920

Woven from the archive, old maps, post office records, the National Register and the people born here.

  1. 19th century
  2. 1895Post officeThe Thermalito post office opens
  3. 20th century
  4. 1912On the mapFirst mapped by the U.S. Geological Survey
  5. 1920Post officeThe Thermalito post office closes
By decade

No old photos in the archives yet

Weddings on Main Street, storms, parades, school pictures, the old store. If it’s in your family album, it belongs here.

Be the first to add onePhotograph a print flat, in daylight, no flash.
Add from your album
People over time

Thermalito, census by census

02,0004,0006,0008,000198020002020Peak: 7,198

Between 4,217 and 7,198 people in every census since 1970.

6 censuses, 1970–2020.

U.S. Census Bureau decennial counts, from the census table on Thermalito’s Wikipedia page.

Famous people

Famous people close to Thermalito

Nobody well known was born in Thermalito itself, so here are the best known from just nearby.

See all →
Aaron RodgersAmerican football player · b. 1983
Doug LaMalfaAmerican politician and businessman · b. 1960
D
Donovan ScottAmerican actor · b. 1947
Pat MastelottoAmerican musician · b. 1955
Jack YermanAmerican sprinter · b. 1939
Brian CageAmerican professional wrestler · b. 1984
Places that used to be

Lost post offices

Thermalito had its own post office from 1895 to 1920.

Thermalito
1895–1920
18901960today

US Post Offices dataset (Blevins & Helbock, CC0). Places and cemeteries from the USGS Geographic Names Information System (2021).

Stories next door

History across the town line

Each neighbor’s History grade, on the same three inputs.

Oroville5 historic placesB+

Questions about Thermalito’s history

What year was Thermalito founded?

The Thermalito post office opened in 1895, the earliest record of the town by name (U.S. post office records).

How does Thermalito rank for history?

Thermalito is more historic than 33% of U.S. towns, #306 of 847 in California. 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.

How old are the homes in Thermalito?

13% of Thermalito’s homes were built before 1940 (Census estimate, ±7.1 points), against a typical 3.4% for a California town; the median home was built in 1969.

Memory lane

What the archives can’t tell you, neighbors can.

Town Square →
Start a conversation
Sources

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 U.S. Geological Survey historical maps, U.S. Census counts (via Wikipedia), 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.