The story so far
Alum Rock, in brief
Wikipedia doesn’t have a history of Alum Rock yet. The photos, dates and memories neighbors add here are how it gets written.
Between the 2010 and 2020 censuses its population fell from 15,536 to 12,042 (-22%).
CHistory
History · Alum Rock
Half of Alum Rock’s homes were built after 1953
More historic than 30% of U.S. towns · #339 of 847 in California. What drives it
Most of Alum Rock was built recently: 10% of its homes predate 1940 and the median home dates from 1953. Below: maps from 1889 on and old-book passages.
0on the National Register
10%homes built before 1940
Quick answers
About Alum Rock’s history
How historic is Alum Rock?
C
What drives the grade ↓More historic than 30% of U.S. towns, on its age, its old homes and the National Register.
History grade
What drives Alum Rock’s History grade
On its age, its old homes and the National Register, Alum Rock is more historic than 30% of U.S. towns, #339 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 Alum Rock’s overall grade.
Founding eraNo founding year we can rely on, so the grade uses the other two–Homes built before 19409.9% of homes (±4.0) · 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 30%
NewerOlder
California towns of 2,500+ (847)Ahead of 60%
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 Alum Rock’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 two of the three inputs, so a change in either one moves the letter more than it would with three. The pre-1940 share is a Census survey estimate (±4.0 points).
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 →
What stands out about Alum Rock’s past
Read from the archive, the National Register and the record. The page puts what stands out first.
★ What stands out · Help out
Start Alum Rock’s collection
The first neighbors to add old photos shape how Alum Rock’s history is told.
Decades since 1900 with photos
00s10s20s30s40s50s60s70s80s90s
0 of 10 decades. The empty ones are waiting for someone’s album.On the map
Alum Rock on the map, 1889 to 1980
Every edition of the U.S. Geological Survey’s map of Alum Rock. Tap a year, or press play to watch the town change.
1889San Jose sheet · 1:62,500U.S. Geological Survey historical topographic maps (public domain), via Esri’s collection of the scans. The red ring marks the center of Alum Rock.
From the old history books
What they wrote about Alum Rock in 1922
Passages that mention Alum Rock, cut from the printed page as they were published.
History of Santa Clara County California1922 · page 1307Read the page →
Read the text
school and an addition to the County Hospital, and is now building six bridges in Monterey and Santa Clara counties, two of them being 340 feet long; he also built the Alum Rock and Keyes Street bridges, three bridges on the Almaden Road and three on Pleasanton Road. He has erected many fine residences and bungalows in San Jose, as well as over the valley, and employs some fifty men.
Text read by machine from the scan; it may contain errors.
History of Santa Clara County, California, with biographical sketches of the leading men and women of the county who have been identified with its growth and development from the early days to the present1922 · page 1307Read the page →
Read the text
school antl an addition to the County Hospital, and is now building six bridges in Monterey and Santa Clara counties, two of them being 340 feet long; he also built the Alum Rock and Keyes Street bridges, three bridges on, the Almaden Road and three on Pleasanton Road. He has erected many line residences and bungalows in San Jose, as well as over the valley, and employs some fifty men.
Text read by machine from the scan; it may contain errors.
History of Santa Clara County California1922 · page 1522Read the page →
Read the text
one on Prospect Road near Saratoga at a cost of $7,700. This bridge is very artistic and architecturally beautiful He also built the $8,000 bridge across Penetencia Creek near Alum Rock, which is also a
Text read by machine from the scan; it may contain errors.
History of Santa Clara County, California, with biographical sketches of the leading men and women of the county who have been identified with its growth and development from the early days to the present1922 · page 1191Read the page →
Read the text
v. S. Steel Corporation. The next year, 1904, he came to Palo Alto and became interested in the building of the Peninsular Railway from Palo Alto to Alum Rock Park, an electric line, now a part of the Southern Pacific Railroad System. John 1'". Parkinson was the main projector of this road, hut Mr. De Forest acquired an active interest. Now he has an office in the Rialto Building in San Francisco, and
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.
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 albumFamous people
See all →Famous people close to Alum Rock
Nobody well known was born in Alum Rock itself, so here are the best known from just nearby.
S
Steve WozniakAmerican computer pioneer, inventor, computer e… · b. 1950
A
Aaron EckhartAmerican actor · b. 1968Stories next door
History across the town line
Each neighbor’s History grade, on the same three inputs.
Questions about Alum Rock’s history
How does Alum Rock rank for history?
Alum Rock is more historic than 30% of U.S. towns, #339 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 Alum Rock?
10% of Alum Rock’s homes were built before 1940 (Census estimate, ±4.0 points), against a typical 3.4% for a California town; the median home was built in 1953.
Memory lane
What the archives can’t tell you, neighbors can.
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 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.