Penngrove
Census-designated place
Main Street in Penngrove
Penngrove Location in the state of California Show map of California Penngrove Penngrove (the United States) Show map of the United States
Coordinates: 38°17′59″N 122°40′0″W / 38.29972°N 122.66667°W / 38.29972; -122.66667[1]
Country	United States
State	California
County	Sonoma
Area [2]
• Total	4.024 sq mi (10.423 km2)
• Land	4.024 sq mi (10.423 km2)
• Water	0 sq mi (0 km2)  0%
Elevation [1]	85 ft (26 m)
Population  (2020)
• Total	4,172
• Density	1,000/sq mi (400/km2)
Time zone	UTC−8 (Pacific)
• Summer (DST)	UTC−7 (PDT)
ZIP code	94951
Area code	707
FIPS code	06-56476
GNIS feature IDs	230491, 2583110

Penngrove is a census-designated place (CDP) in Sonoma County, California, United States, situated between the cities of Petaluma and Cotati, at the foot of the western flank of Sonoma Mountain. It is part of the North Bay subregion of the San Francisco Bay Area. The population was 2,522 at the 2010 census.

The area is the site of a historic grove called Penn's Grove;^[3] it was formerly a freight station on the Northwestern Pacific Railroad and a center of egg and chicken farming.

Penngrove's downtown consists of Main Street, a 0.3-mile (0.48 km) street linking Old Redwood Highway to Adobe Road. Penngrove School is located at the corner of Adobe Road, where Main Street becomes Petaluma Hill Road.^[4]

Lichau Creek flows southward through the town, paralleling the railway. The creek feeds into the Petaluma River, which flows to San Pablo Bay.

Due to the Sonoma Mountain's ancient volcanism, Penngrove is rich with obsidian and petrified wood. Its soil is unique, composed mainly of clay-like adobe, which has been used for centuries as building material. A prime example of adobe architecture is the Rancho Petaluma Adobe, a State Historic Park in nearby Petaluma.

Penngrove enjoys a mild Mediterranean climate.

According to the United States Census Bureau, the CDP covers an area of 4 square miles (10.4 km²), all of it land.

The 2010 United States Census^[5] reported that Penngrove had a population of 2,522. The population density was 626.7 inhabitants per square mile (242.0/km²). The racial makeup of Penngrove was 2,212 (87.7%) White, 19 (0.8%) African American, 24 (1.0%) Native American, 54 (2.1%) Asian, 2 (0.1%) Pacific Islander, 112 (4.4%) from other races, and 99 (3.9%) from two or more races. Hispanic or Latino of any race were 292 persons (11.6%).

The Census reported that 99.6% of the population lived in households and 0.4% lived in non-institutionalized group quarters.

There were 1,040 households, out of which 260 (25.0%) had children under the age of 18 living in them, 483 (46.4%) were opposite-sex married couples living together, 117 (11.3%) had a female householder with no husband present, 65 (6.3%) had a male householder with no wife present. There were 80 (7.7%) unmarried opposite-sex partnerships, and 10 (1.0%) same-sex married couples or partnerships. 285 households (27.4%) were made up of individuals, and 83 (8.0%) had someone living alone who was 65 years of age or older. The average household size was 2.42. There were 665 families (63.9% of all households); the average family size was 2.89.

The population was spread out, with 442 people (17.5%) under the age of 18, 244 people (9.7%) aged 18 to 24, 585 people (23.2%) aged 25 to 44, 889 people (35.2%) aged 45 to 64, and 362 people (14.4%) who were 65 years of age or older. The median age was 44.8 years. For every 100 females, there were 98.4 males. For every 100 females age 18 and over, there were 99.0 males.

There were 1,120 housing units at an average density of 278.3 per square mile (107.5/km²), of which 61.5% were owner-occupied and 38.5% were occupied by renters. The homeowner vacancy rate was 1.4%; the rental vacancy rate was 3.1%. 64.6% of the population lived in owner-occupied housing units and 35.0% lived in rental housing units.

The Mexican government granted Rancho Cotate to Captain Juan Castaneda in July 1844 for his military services in the region.^[6][7] 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."^[7]

Rancho Cotate was sold in 1849 to Dr. Thomas S. Page of Cotati, and eventually broken up and sold off piecemeal to incoming settlers.^[6]

The first European settlers in the Penngrove area were David Wharff, W.J. Hardin, and J.M. Palmer, who arrived in 1852.^[8]

In October 1870, the San Francisco and North Pacific Railroad completed the first railroad from Petaluma to Santa Rosa, running through Penngrove.^[6]

Every summer on the Sunday closest to July 4, Penngrove celebrates the 4th of July with a parade sponsored by the Penngrove Social Firemen. On Saturday at the Penngrove Fire Station, located at the corner of Main Street and Old Redwood Highway, the Rancho Adobe Firefighters' Association sponsors a breakfast.^[9][10]

It is in the Petaluma City Elementary School District and the Petaluma Joint Union High School District.^[11]

The naming of Penngrove is uncertain; there are three main "histories" of the name's origin.

Ruth Anderson, the famous "Bell-Lady" of Penngrove (who lived on the site of the old schoolhouse on Oak Street), recalls, "In the late 1860s, two brothers by the name of Penn came out from Pennsylvania and bought 80 acres (320,000 m²) of land in this area. They planted the area with olive trees, but when the trees matured it was found that the olives were not edible. The Penn brothers tore out many of the groves, sold the land and moved away. However, while they were here, they named their place Penn's Grove. Later it was changed to "Penn Grove,"^[12] and still later, because our mail got confused with that of Pine Grove (the former name of Sebastopol), the U.S. Postoffice Department changed the name to one word—Penngrove." (Harris 1980)

Other accounts state that because there was another town with the name of Penn's Grove in New Jersey, this could be a reason as to why the post office changed the name. Others claim that the Woodward family, who came from Pennsylvania, named their property Penn's Grove in honor of their home state.^[3]

Along with the chicken and egg industry, Penngrove was a source of basalt paving stones, which were used to pave the streets of major cities in the Bay Area, including San Francisco. Harris notes that 200 men were employed at the three major cobblestone quarries at the end of the 19th century, and that quarry scars can still be seen dotting the hills between East Railroad Avenue and Roberts Road. When the Northwestern Pacific Railroad was completed in 1870, the paving stone industry kept Penngrove station busy. After the turn of the century, Penngrove became the "second largest egg and poultry producing area in the country. Only Petaluma outdid this area" (Harris 1980). Apparently, according to The San Francisco Examiner, chickens paid better than gold mines. To this day, many dilapidated chicken houses dot old farms and country roads in the area.

One of the oldest buildings in Penngrove, the old Methodist Episcopal Church was built in 1898 at the corner of Formschlag Lane and Petaluma Hill Road. In 1910, the church was moved on wooden rollers to its present location at 9970 Oak Street. The original building now serves as a fellowship hall, while a newer structure, built in 1955–1957, now serves as the main sanctuary. The original structure is still used by Girl Scouts of the USA, Boy Scouts of America, 4-H, and various other community organizations.

The first classes were taught in a small building on Peters' Ranch (Harris 1980: 33). In 1876, the first school was built at the southwest corner of Adobe Road and Main Street. It was named the Eagle School after the Eagle Hotel located across Main Street and shown on Thompson's map of Sonoma County (1877). In 1906 after construction of the second Eagle School, the old school was used as a teacher's residence. It was later moved about 50 ft (15 m) south to its current location and reconfigured into an ell. The second Eagle School was built between Main and Oak streets. The original structure no longer exists, and a private home now stands on that property, however, the steps leading to "Eagle School" from Main Street are still visible. Some of building materials were recycled for construction of the Community Center and a small building in Penngrove Park. In 1926 a beautiful mission-style school house was built and named Penngrove School, Eagle District. Penngrove School joined the Petaluma City School District in 1962. In 1963, the present multi-purpose room was constructed and newer wings were developed between it and the older portion of the school. The multi-purpose room was expanded with a stage in 2006. The 1926 school building is now primarily used for offices and the school library.

"The Post Office at Penn's Grove was established on October 30, 1882. A series of name changes occurred because of mail mix-ups with Penn's Grove, New Jersey and Pine Grove (later renamed Sebastopol). In May 1895 the Petaluma paper reported: 'The Penngrove Post Office has had its name changed again and is now officially known by its former and best known title, Penn's Grove.' In 1908 the name was changed back to Penngrove and has remained so since" (Harris 1980). The first Post Office was located in the Edwards Building and was then moved into the Terribilini Building on the East side of Main Street. It was then moved next to Penngrove Market and a new structure for the Post Office was built in the 1980s on Main Street across from Penngrove Market.

At the turn of the century, three fire chemical carts served as Penngrove's fire protection. The foundation of Firehouse #1 can be found between Penngrove Church and the Old Eagle School lot on Oak Street. "The fire department was established in the fall of 1928. In 1929 the first fire engine was put into service" (Harris 1980). In 1938, the art deco fire house was built on Woodward Avenue, just above Main Street. This structure still bears the title "Penngrove Firehouse." It is a now a private residence. In 1975, the current firehouse was built at the corner of Old Redwood Highway and Main Street, the unofficial entrance to Penngrove. Until the 1990s, a siren placed at the top of the building would sound in order to alert volunteer firefighters of a fire. The siren had a greater than 1.5-mile (2.4 km) radius and could be heard frequently through the hot, dry summer months. This system was replaced by pagers in the 1990s, although the siren remains perched on top of the firehouse. Currently, the Penngrove Firehouse is part of the Rancho Adobe Fire District, along with Cotati and other surrounding communities.

"During World War I, a group of Penngrove ladies met in Evart's Hall to do Red Cross work. After the war they decided they wanted to stay together as a group and have a club house of their own" (Harris 1980: 33). In 1922, after raising funds and materials, Penngrove came together to build the Community Club House. The total cost was $9,000. The building was first named the "Penngrove Social Welfare Club House", but was later shortened to Penngrove Women's Club House. After a fire destroyed portions of the building in the late 1970s and the Women's Club could no longer afford the upkeep, the Penngrove Social Firemen bought the building. It is now used for various community events, such as voting and fundraisers.

"The Bank Building was built in 1922 for the Central Commercial and Savings Bank. The bank lasted only 2 or 3 years. The bank manager and his family lived upstairs" (Harris 1980: 48).

The Penngrove Rail Station burned to the ground in 1980, and nothing of it survives. The poultry loading docks still exist behind Penngrove Market, adjacent to Penngrove Park, and now house businesses.

• DeClercq, John H. (1977). History of Rohnert Park "from seed to city". Rohnert Park, California: Rohnert Park, Calif. : City Council. Retrieved October 29, 2020 – via Gaye LeBaron Collection.
• Harris, Ellen M. (January 1, 1980). Penngrove: A Jigsaw Puzzle of Its Past and Present. Penngrove, California.{{cite book}}: CS1 maint: location missing publisher (link)

• Thompson, Robert A. (1877). Thos H. Thompson & Co (ed.). Historical Atlas Map of Sonoma County, California (1970 ed.). Mid-Cal Publishers. Retrieved October 29, 2020.
• Lightfoot, Kent; Parrish, Otis (2009). California Indians and Their Environment: An Introduction. Berkeley: University of California Press. ISBN 978-0-520-94228-8.
• Torliatt, Lee (June 20, 2001). Golden Memories of the Redwood Empire. Arcadia Publishing. ISBN 978-1-4396-1317-7. Retrieved October 29, 2020.

• Miwok Indians from Access Genealogy, a list of all verified Coastal Miwok villages in the area

• Historical Penngrove Images at the Sonoma County Library Digital Collections
• 2020 US Census Data for 94951 Penngrove, CA