Penngrove, California, United States

🇺🇸 Penngrove is a 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 area is the site of a historic grove called Penn's Grove; it was formerly a freight station on the Northwestern Pacific Railroad and a centre of egg and chicken farming.

The North Bay is connected to San Francisco by the Golden Gate Bridge and to the East Bay by the Richmond–San Rafael Bridge, Carquinez Bridge and the Benicia–Martinez Bridge. Several ferry routes operate between the North Bay and San Francisco, from terminals located in Angel Island, Larkspur, Sausalito, Tiburon and Vallejo.

The Sonoma–Marin Area Rail Transit (SMART), a commuter rail line from Larkspur to Cloverdale, was approved by voters in November 2008. Passenger service began between the Sonoma County Airport station and San Rafael in August 2017 and was completed as far south as Larkspur in 2019.

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.

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.

Community development 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.