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C+History
History · Hamilton City

Hamilton City’s post office opened in 1906, and 10% of its homes were built before 1940

More historic than 37% of U.S. towns. What drives it

Its Register listing is the Gianella Bridge. Below: 1 old photo or paper, maps from 1914 on, and the census since 1980.

1906first post office
1on the National Register
10%homes built before 1940
1old photo or paper
1famous people
Add an old photoShare a memory
From Hamilton City’s archive · credits on each photo
Quick answers

How Hamilton City began

When was Hamilton City founded?

1906

The Hamilton City post office opened in 1906, the earliest record of the town by name.

First census: 1,337 in 19802020 census: 2,263120 years

How historic is Hamilton City?

C+

More historic than 37% of U.S. towns, on its age, its old homes and the National Register.

What drives the grade ↓
Founding year: the first Hamilton City post office (Blevins & Helbock, CC0).The full story ↓
History grade

What drives Hamilton City’s History grade

On its age, its old homes and the National Register, Hamilton City is more historic than 37% of U.S. towns. Its National Register listings hold the grade up; its age pulls it down.

C+
HistoryA character grade: shown, never part of Hamilton City’s overall grade.
Founding era1906, from the first post office: founded 1900–1944, an older era than 9% of U.S. townsDHomes built before 194010.0% of homes (±5.8) · typical CA town 3.4% · U.S. 8.4%B−National Register1 listing, 4.4 per 10,000 residents · typical CA town 0.0 · U.S. 2.4B+
All U.S. towns we grade (21,289)Ahead of 37%
NewerOlder

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 Hamilton City’s 4.4 sits above most of its state (87% of California towns have fewer) while its 1 listings outnumber those of 51% 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 (±5.8 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 Hamilton City’s past

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

A history waiting to be writtenOnly 1 old photo is in the public archives. The rest are in attics and albums.On the map since 19144 editions of the USGS map, 1914 to 1969. Watch Hamilton City change.
★ What stands out · Help out

Start Hamilton City’s collection

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

Decades since 1900 with photos
00s10s20s30s40s50s60s70s80s90s
0 of 10 decades. The empty ones are waiting for someone’s album.
Date a photo1 archive item has no date. Guess the decade.+2Retake an old viewEnd CA 45: stand where they stood+15Share a family photoSign in to add one+10
On the map

Hamilton City on the map, 1914 to 1969

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

Hamilton City on the 1914 USGS mapHamilton City on the 1949 USGS mapHamilton City on the 1950 USGS mapHamilton City on the 1969 USGS map1914Hamilton 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 Hamilton City.

The story

How Hamilton City came to be

From Wikipedia’s history of Hamilton City.

Read it all →

The town began in 1905 with the founding of a large sugar beet processing plant, completed the following year by James Hamilton and the Alta California Sugar Beet Company (which changed its name in 1908 to Sacramento Valley Sugar Company). The plant later belonged to Holly Sugar Corporation and is known to this day as the Holly Sugar Plant. Holly Sugar was sold in 1936 to Spreckels Sugar Company and, in turn, Spreckels was later purchased by Imperial Sugar. The sugar plant closed in 2006, and in 2021 was acquired and renovated by Nutrien Company, a fertilizer producer.

Text from Wikipedia, licensed CC BY-SA 4.0.

Timeline

Hamilton City, 1878 to 1914

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

  1. 19th century
  2. 1878Born hereSherman Reynolds is born here
  3. 20th century
  4. 1906Post officeThe Hamilton City post office opens
  5. 1914On the mapFirst mapped by the U.S. Geological Survey
By decade

Hamilton City, decade by decade

Date unknown1 to date
End CA 45Date?End CA 45
Today4 recent
Holly Sugar Plant, Hamilton City (2024)-L10054712024Holly Sugar Plant, Hamilton City (2024)-L1005471Holly Sugar Plant, Hamilton City (2024)-L10054652024Holly Sugar Plant, Hamilton City (2024)-L1005465Post Office in Hamilton City, California-L10031662023Post Office in Hamilton City, California-L1003166Ham City Project, March 20112014Ham City Project, March 2011
Then & now

Stand where they stood

No then-and-now pairs yet. Take a photo from the same spot as an old one and they appear here side by side.

End CA 45
Retake this viewEnd CA 45

Find the spot, match the angle, and add your photo. It becomes the first then-and-now pair on Hamilton City’s page.

Retake this view · +15
On the National Register

1 historic place in Hamilton City

The country’s official list of buildings and places worth saving.

place listed
1
National Historic Landmarks
0
none yet
historic buildings protected
1
each building in a district counts
first listed
1982
Gianella Bridge
Structures
Gianella BridgeStructure

National Park Service, National Register of Historic Places. Photos from Wikimedia Commons, credited on each place’s page.

People over time

Hamilton City, census by census

05001,0001,5002,0002,500198020002020Peak: 2,263

Between 1,337 and 2,263 people in every census since 1980.

5 censuses, 1980–2020.

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

Places that used to be

Old corners

Hamilton City’s post office has been open since 1906.

Hamlets and corners on the map
Ideal Mobile Home Park

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

Questions about Hamilton City’s history

What year was Hamilton City founded?

The Hamilton City post office opened in 1906, the earliest record of the town by name (U.S. post office records).

How does Hamilton City rank for history?

Hamilton City is more historic than 37% 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 Hamilton City?

One place: the Gianella Bridge (listed 1982).

How old are the homes in Hamilton City?

10% of Hamilton City’s homes were built before 1940 (Census estimate, ±5.8 points), against a typical 3.4% for a California town; the median home was built in 1974.

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 Wikimedia Commons (5), the National Register of Historic Places (1), Wikipedia, Wikidata and Wikipedia for famous people, 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.