The Los Alamos post office opened in 1877, the earliest record of the town by name. Another post office, Los Alisos (1870), opened inside today’s town and later closed.
First census: 1,372 in 20002020 census: 1,839149 years
How historic is Los Alamos?
C+
More historic than 38% of U.S. towns, on its age, its old homes and the National Register.
Founding year: the first Los Alamos post office (Blevins & Helbock, CC0).The full story ↓
History grade
What drives Los Alamos’ History grade
On its age, its old homes and the National Register, Los Alamos is more historic than 38% of U.S. towns. 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 Los Alamos’ overall grade.
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 Los Alamos’ 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 B−. The pre-1940 share is a Census survey estimate (±18.1 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 Los Alamos’ past
Read from the archive, the National Register and the record. The page puts what stands out first.
Fire insurance maps drew every building, what it was made of and what it was used for, so insurers could price the risk of fire. Pick a year, then a sheet.
1886Sheet 1 of 1
Edition
Sheets
BrickWoodStone
Sanborn Map Company, via the Library of Congress. Editions published in 1930 or earlier, which are in the public domain.
In 1839, José Antonio de la Guerra, a son of José de la Guerra y Noriega received the Rancho Los Alamos Mexican land grant. The hills above Rancho Los Alamos served as a hideout for bandito Salomon Pico, whose escapades were popularized by the character "Zorro". During the U.S.'s centennial year of 1876, Thomas Bell along with his nephew John S. Bell, and Dr. James B. Shaw (all from San Francisco), purchased acreage from Rancho Los Alamos and neighboring Rancho La Laguna. Both families allocated a half square mile from each of their new ranches to create the Los Alamos town site with "Centennial Street" as the central thoroughfare.
Nothing in the archives for these yearsWeddings on Main Street, storms, parades, school pictures, the old store. If it’s in your family album, it belongs here.
Between 1,372 and 1,890 people in every census since 2000.
3 censuses, 2000–2020.
U.S. Census Bureau decennial counts, from the census table on Los Alamos’ Wikipedia page.
Places that used to be
Lost post offices and burying grounds
Los Alamos’s post office has been open since 1877. Another post office, Los Alisos, opened and closed inside today’s town.
Los Alisos
1870–1871
Los Alamos
1877–today
18701950today
1cemetery inside Los Alamos
Los Alamos
US Post Offices dataset (Blevins & Helbock, CC0). Places and cemeteries from the USGS Geographic Names Information System (2021).
Questions about Los Alamos’ history
What year was Los Alamos founded?
The Los Alamos post office opened in 1877, the earliest record of the town by name (U.S. post office records).
How does Los Alamos rank for history?
Los Alamos is more historic than 38% 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.
How old are the homes in Los Alamos?
17% of Los Alamos’ homes were built before 1940 (Census estimate, ±18.1 points), against a typical 3.4% for a California town; the median home was built in 1995.
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 Wikimedia Commons (10), the Library of Congress (1), Wikipedia, U.S. Geological Survey historical maps, U.S. Census counts (via Wikipedia), the US Post Offices dataset (Blevins & Helbock), the USGS Geographic Names Information System and Sanborn fire insurance maps (Library of Congress). Archive images are copied here with their credits and licenses, shown on each photo’s page. Refreshed monthly.
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