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C+History
History · Penngrove

Penngrove’s post office opened in 1894, and 19% of its homes were built before 1940

More historic than 40% of U.S. towns. What drives it

Below: maps from 1911 on.

1894first post office
0on the National Register
19%homes built before 1940
1famous people
Add an old photoShare a memory
Photo: Stephen R. Gold · Public domain
Quick answers

How Penngrove began

When was Penngrove founded?

1894

The Penngrove post office opened in 1894, the earliest record of the town by name. Two smaller post offices, Penn (1882) and Penns Grove (1883), opened inside today’s town and later closed.

2020 census: 2,637132 years

How historic is Penngrove?

C+

More historic than 40% of U.S. towns, on its age, its old homes and the National Register.

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

What drives Penngrove’s History grade

On its age, its old homes and the National Register, Penngrove is more historic than 40% 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 Penngrove’s overall grade.
Founding era1894, from the first post office: founded 1850–1899, an older era than 37% of U.S. townsC+Homes built before 194018.6% of homes (±9.5) · 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 40%
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 Penngrove’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 any two of the three inputs instead, the letter would range from C− to B−. The pre-1940 share is a Census survey estimate (±9.5 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 Penngrove’s past

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

A history waiting to be writtenNo old photos of Penngrove are in the public archives yet. The rest are in attics and albums.Lost villages2 post offices opened and closed inside today’s Penngrove.On the map since 19166 editions of the USGS map, 1916 to 1980. Watch Penngrove change.
★ What stands out · Help out

Start Penngrove’s collection

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

Decades since 1900 with photos
00s10s20s30s40s50s60s70s80s90s
0 of 10 decades. The empty ones are waiting for someone’s album.
Share a family photoSign in to add one+10
Places that used to be

Lost post offices

Penngrove’s post office has been open since 1894. Two other post offices opened and closed inside today’s town.

Penn
1882–1883
Penns Grove
1883–1894
Penngrove
1894–today
18801950today

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

On the map

Penngrove on the map, 1916 to 1980

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

Penngrove on the 1916 USGS mapPenngrove on the 1944 USGS mapPenngrove on the 1954 USGS mapPenngrove on the 1968 USGS mapPenngrove on the 1973 USGS mapPenngrove on the 1980 USGS map1916Santa Rosa sheet · 1:62,500

U.S. Geological Survey historical topographic maps (public domain), via Esri’s collection of the scans. The red ring marks the center of Penngrove.

The story

How Penngrove came to be

From Wikipedia’s history of Penngrove.

Read it all →

The Mexican government granted Rancho Cotate to Captain Juan Castaneda in July 1844 for his military services in the region. The grant encompassed present-day Penngrove, Cotati and Rohnert Park. Cotate Rancho is a part of Vallejo Township which encompasses the plain between Sonoma Mountain and Petaluma Creek, San Pablo Bay, with an east–west line dividing the tract from Santa Rosa Township."

Rancho Cotate was sold in 1849 to Dr. Thomas S. Page of Cotati, and eventually broken up and sold off piecemeal to incoming settlers.

The first European settlers in the Penngrove area were David Wharff, W.J. Hardin, and J.M. Palmer, who arrived in 1852.

Text from Wikipedia, licensed CC BY-SA 4.0.

Timeline

Penngrove, 1882 to 1983

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

  1. 19th century
  2. 1882Post officeThe Penn post office opens
  3. 1883Post officeThe Penn post office closes
  4. 1883Post officeThe Penns Grove post office opens
  5. 1894Post officeThe Penns Grove post office closes
  6. 1894Post officeThe Penngrove post office opens
  7. 20th century
  8. 1916On the mapFirst mapped by the U.S. Geological Survey
  9. 1983Born hereJustin Rogers is born here
By decade

Penngrove, decade by decade

Today7 recent
2011-365-146 My Street20112011-365-146 My Street1944 International20091944 International1940-41 Graham Hollywood20091940-41 Graham Hollywood1928 Buick20091928 BuickPenngrove28822008Penngrove2882LichauCr28802008LichauCr2880Photo-CA-Penngrove2006Photo-CA-Penngrove
Every building

Penngrove, building by building, 1911

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 sheet.

Penngrove fire insurance map, 1911, sheet 11911Sheet 1 of 1
Sheets
BrickWoodStone

Sanborn Map Company, via the Library of Congress. Editions published in 1930 or earlier, which are in the public domain.

Questions about Penngrove’s history

What year was Penngrove founded?

The Penngrove post office opened in 1894, the earliest record of the town by name (U.S. post office records).

How does Penngrove rank for history?

Penngrove is more historic than 40% 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 Penngrove?

19% of Penngrove’s homes were built before 1940 (Census estimate, ±9.5 points), against a typical 3.4% for a California town; the median home was built in 1972.

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 (7), Wikipedia, Wikidata and Wikipedia for famous people, U.S. Geological Survey historical maps, 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.