4 places in town are on the National Register, among them a historic district with 61 buildings. Most of Mariposa was built recently: 4% of its homes predate 1940 and the median home dates from 1975. Below: 2 old photos and papers from 1861 on and old-book passages.
Founding year: the first Mariposa post office (Blevins & Helbock, CC0).The full story ↓
History grade
What drives Mariposa’s History grade
On its age, its old homes and the National Register, Mariposa is more historic than 54% of U.S. towns. Its National Register listings hold the grade up; its share of homes from before 1940 pulls it down.
B−
HistoryA character grade: shown, never part of Mariposa’s 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 Mariposa’s 572 sits above most of its state (100% of California towns have fewer) while its 65 historic buildings outnumber those of 87% 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 (±6.0 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 Mariposa’s past
Read from the archive, the National Register and the record. The page puts what stands out first.
Before Spanish arrival, the Southern Sierra Miwok lived in what is now Mariposa. In 1806, a Spanish priest traveling with early California explorer Gabriel Moraga named the area. When the expedition came upon a creek filled with thousands of yellow butterflies, they called it “Las Mariposas,” the Spanish word for butterflies.
Passages that mention Mariposa, cut from the printed page as they were published.
A memorial and biographical history of the counties of Merced, Stanislaus, Calaveras, Tuolumne and Mariposa, California1892 · page 192Read the page →
Read the text
The population of the town of Mariposa is now about 600, and much of the importance that now attaches to the town is by virtue of its historic past, the fact of its being the headquarters for county business, and lastly, tbe hope for the future.
Text read by machine from the scan; it may contain errors.
A memorial and biographical history of the counties of Merced, Stanislaus, Calaveras, Tuolumne and Mariposa, California1892 · page 63Read the page →
Read the text
The county of Merced was formed under an act of the Legislature of 1855, being set off from Mariposa, then represented by As serablymen Thomas Flournoy and E. Burke, and Major A. McNeill, Senator. The bill, which was approved by Governor Bigler, April 19, 1855, provided for a Board of Commissioners, which was constituted as follows:
Text read by machine from the scan; it may contain errors.
Scans and text from the Internet Archive. Books published in 1930 or earlier, which are in the public domain.
Timeline
Mariposa, 1851 to 1979
Woven from the archive, old maps, post office records, the National Register and the people born here.
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.
Mariposa DistrictMariposa International Order of Odd FellowsMariposa MasonicSaint Joseph
US Post Offices dataset (Blevins & Helbock, CC0). Places and cemeteries from the USGS Geographic Names Information System (2021).
Questions about Mariposa’s history
What year was Mariposa founded?
The Mariposa post office opened in 1851, the earliest record of the town by name (U.S. post office records).
How does Mariposa rank for history?
Mariposa is more historic than 54% 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 Mariposa?
4 listings: 3 buildings, among them the Mariposa County Courthouse (listed 1977, the first), and 1 historic district, the Mariposa Town Historic District, with 61 contributing buildings. 65 historic buildings in all.
How old are the homes in Mariposa?
4% of Mariposa’s homes were built before 1940 (Census estimate, ±6.0 points), against a typical 3.4% for a California town; the median home was built in 1975.
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 (5), Wikidata (1), the National Register of Historic Places (4), Wikipedia, Wikidata and Wikipedia for famous people, the US Post Offices dataset (Blevins & Helbock), the USGS Geographic Names Information System and old county and town histories (Internet Archive). Archive images are copied here with their credits and licenses, shown on each photo’s page. Refreshed monthly.
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