Each edition grades its towns against each other only.
More historic than 16% of U.S. towns · #569 of 847 in California. What drives it
Most of Castro Valley was built recently: 3% of its homes predate 1940 and the median home dates from 1966. Below: maps from 1899 on and the census since 1940.
More historic than 16% of U.S. towns, on its age, its old homes and the National Register.
On its age, its old homes and the National Register, Castro Valley is more historic than 16% of U.S. towns, #569 of 847 in California. 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 Castro Valley’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.
Founding year: our sources. 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 →
Read from the archive, the National Register and the record. The page puts what stands out first.
The first neighbors to add old photos shape how Castro Valley’s history is told.
Every edition of the U.S. Geological Survey’s map of Castro Valley. Tap a year, or press play to watch the town change.
U.S. Geological Survey historical topographic maps (public domain), via Esri’s collection of the scans. The red ring marks the center of Castro Valley.
Writers, athletes, leaders and more, ranked by how widely they’re known.
From Wikipedia’s history of Castro Valley.
Before the arrival of European settlers the area was settled by the Chocheño (also spelled Chochenyo or Chocenyo) subdivision of the Ohlone Native Americans.
With the arrival of Europeans, they established Mission San Jose in 1797. The area Castro Valley now occupies was part of the extensive colony of New Spain in what was the province of Alta California.
Text from Wikipedia, licensed CC BY-SA 4.0.
Woven from the archive, old maps, post office records, the National Register and the people born here.
Grew from 4,145 people in 1940 to 66,441 in 2020, more than tenfold.
8 censuses, 1940–2020.
U.S. Census Bureau decennial counts, from the census table on Castro Valley’s Wikipedia page.
Places and cemeteries from the USGS Geographic Names Information System (2021).
Each neighbor’s History grade, on the same three inputs.
Castro Valley is more historic than 16% of U.S. towns, #569 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.
3% of Castro Valley’s homes were built before 1940 (Census estimate), against a typical 3.4% for a California town; the median home was built in 1966.
What the archives can’t tell you, neighbors can.
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 (6), Wikipedia, Wikidata and Wikipedia for famous people, U.S. Geological Survey historical maps, U.S. Census counts (via Wikipedia) 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.
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