Sonoma County, California

Sonoma County is a county in the northern part of the U.S. state of California. As of the 2020 United States census, it had a population of 488,863 people. The largest city and seat of government is Santa Rosa.

The county is part of the Santa Rosa-Petaluma metropolitan statistical area, which is within the larger San Jose-San Francisco-Oakland combined statistical area. It is the northernmost county in the San Francisco Bay Area region.

Sonoma County is well known for its beautiful landscapes and is a big part of California's Wine Country, along with Napa, Mendocino, and Lake counties. It is the largest wine producer in this area, with nineteen approved American Viticultural Areas and over 350 wineries. Each year, more than 8.4 million visitors come to enjoy its scenery and wineries.

The county also grows many important crops, such as hops, grapes, prunes, and apples, and raises dairy and poultry. This is possible because of the rich farmland and plenty of good water for irrigation.

History

Scientific studies of rock formations at Wilson Grove in Sonoma County began in 1952. By 1988, they showed that about 4 million years ago, a shallow sea covered the area, named the Wilson Grove Sea. Wilson Grove, named after Walter Wilson, is near California's Russian River and west of Windsor, California. Fossils of many sea creatures were found there.

The Pomo, Coast Miwok, and Wappo peoples were the first people to live in Sonoma County, arriving between 8000 and 5000 BC. Spaniards, Russians, and other Europeans later came to the area looking for timber, fur, and farmland. The Russians built Fort Ross in 1812 but left in 1841.

Sonoma became one of California’s original counties when the state was formed in 1850, with Sonoma as its first county seat. Later, Santa Rosa became the county seat in 1854. After 1850, towns like Petaluma, Santa Rosa, and Healdsburg grew, especially after railroads arrived.

Sonoma County faced big challenges, like the 1906 San Francisco earthquake and several major wildfires in recent years, including the Tubbs Fire in 2017 and the Kincade Fire in 2019. The county has many historical landmarks recognized by local groups.

	Spanish Empire, 1542, by sea, voyage of Juan Rodríguez Cabrillo as far as the Russian River. Later validated by voyage of Sebastián Vizcaíno, 1602.
	Kingdom of England, June 1579, voyage of the Golden Hind under Captain Francis Drake at Bodega Bay (exact location disputed).
	Spanish Empire, October 1775, the Sonora at Bodega Bay, under Lt. Juan Francisco de la Bodega y Quadra, until 1821, when Mexico gained independence from Spain.
	Russian Empire, by Russian-American Company expedition led by Ivan Alexandrovich Kuskov, the founder of Fort Ross and, from 1812 to 1821, its colonial administrator. Note: There is an overlap of rule with the Mexican Empire (next item), until the Russians sold Fort Ross in 1841 to John Sutter, before leaving the area in 1842.
	First Mexican Empire, August 1821, under Emperor Agustin Iturbide (October 1822, probable time new flag raised in California), until 1823.
	Mexican Republic, 1823 until June 1846.
	California Republic, June 14, 1846, until July 9, 1846.
	United States of America, July 9, 1846 to present.

Etymology

The name Sonoma has many interesting meanings from the past. Local tribes, such as the Coast Miwok and Pomo, said it means "valley of the moon" or "many moons," describing a place where the moon seemed to rest. This idea was first written down in 1850 by General Mariano Guadalupe Vallejo and later became famous in a novel by Jack London titled The Valley of the Moon.

Other ideas about the name come from different local tribes. Some believe it means "earth village" or comes from a word for "nose," perhaps because an early leader had a notable feature. Each story adds to the rich history of the area's name.

Geography

Sonoma County is a place in California that covers an area of 1,768 square miles. It is located in the North Coast Ranges and includes many different types of land, such as mountains, forests, and valleys. The county has several important peaks, like Mt. Saint Helena, and special areas like Jack London State Historic Park.

The county has a variety of climates due to its coastal location and different elevations. Areas closer to the ocean tend to be cooler and foggier, while inland areas can be warmer and sunnier. The county also has many rivers and streams, with the Russian River being a major one. These water bodies support diverse wildlife and habitats.

The county is home to several marine protected areas that help conserve ocean life. It also has many species of plants and animals that need special care to survive.

Transportation

Major highways

U.S. Route 101 is an important road running north and south through California, Oregon, and Washington. In Sonoma County, it connects several cities including Cloverdale, Healdsburg, Windsor, Santa Rosa, Rohnert Park, Cotati, and Petaluma. This road is busy during rush hours, and work is being done to make it wider and better for traffic.

Other important roads in the county include State Route 1 along the coast, State Route 12 connecting Sebastopol to Santa Rosa and beyond, State Route 37 linking Novato to Vallejo, State Route 116 running from Jenner to Sonoma, State Route 121 near Sears Point Raceway, and State Route 128 through the Alexander Valley.

Public transportation

Sonoma County Transit provides bus service throughout the county. Santa Rosa has its own bus system called CityBus. Other cities like Cloverdale and Petaluma also have local buses. Golden Gate Transit connects Santa Rosa to Marin County and San Francisco. Mendocino Transit Authority runs buses north to Ukiah and the coast. Sonoma–Marin Area Rail Transit (SMART) is a train service that started running between Larkspur and Windsor in 2025, with plans to extend further.

Airports

The Charles M. Schulz - Sonoma County Airport near Santa Rosa offers flights on Alaska Airlines, American Airlines, and United Airlines. There are also smaller airports for private planes in Cloverdale, Healdsburg, Petaluma, Sonoma Skypark, and Sonoma Valley.

Railroads

The first railroad in the area connected Petaluma to a ferry in 1864. By 1870, Santa Rosa was linked to ferries, and the railroad grew to reach Healdsburg, Cloverdale, and beyond. Today, the Sonoma–Marin Area Rail Transit uses old railroad paths to bring passengers between Sonoma County and Marin.

Crime

The following table shows the number of reported incidents and the rate per 1,000 people for each type of offense in the year 2009.

Cities by population and crime rates

Demographics

Sonoma County, California, is home to many people. As of the 2020 census, the county had a population of 488,863. The median age was 42.6 years, with many people of different ages living there.

Most people in Sonoma County identified as White, with smaller groups identifying as Black or African American, American Indian and Alaska Native, Asian, Native Hawaiian and Pacific Islander, or from two or more races. Many people also identified as Hispanic or Latino. Most residents lived in urban areas, while some lived in rural areas.

There were many households in the county, some with children and some without. Housing units were either owned or rented by the people living there.

Historical population

Census	Pop.	Note	%±
1850	560		—
1860	11,867		2,019.1%
1870	19,819		67.0%
1880	25,926		30.8%
1890	32,721		26.2%
1900	38,480		17.6%
1910	48,394		25.8%
1920	52,090		7.6%
1930	62,222		19.5%
1940	69,052		11.0%
1950	103,405		49.7%
1960	147,375		42.5%
1970	204,885		39.0%
1980	299,681		46.3%
1990	388,222		29.5%
2000	458,614		18.1%
2010	483,878		5.5%
2020	488,863		1.0%
2025 (est.)	486,444		−0.5%
U.S. Decennial Census 1790–1960 1900–1990 1990–2000 2010 2020 2022

Government

The government of Sonoma County works as a general law county, guided by the California Constitution. It is led by a group of five elected leaders called the Sonoma County Board of Supervisors. These supervisors are chosen by voters in different parts of the county and serve for four years. They also help manage important local services.

Sonoma County has many leaders and groups appointed by the supervisors to help with different jobs. There is a main leader called the county administrator who helps run the county’s work, like managing parks and other services. In 2010, Veronica Ferguson became the first woman to hold this important job.

State and federal representation

Sonoma County is part of different areas in California. In the U.S. Congress, it is split between the 2nd and 4th districts, with representatives Jared Huffman and Mike Thompson. In the California State Assembly, the county is in the 2nd, 4th, and 10th districts, represented by Chris Rogers, Cecilia Aguiar-Curry, and Damon Connolly. In the California State Senate, the county is in the 2nd senatorial district with Mike McGuire, and the 3rd senatorial district with Christopher Cabaldon.

Law enforcement

The Sonoma County Sheriff's Office helps keep the peace in areas of the county that are not part of a city. They also work with the police in the City of Sonoma and the Town of Windsor. The office has many workers, including Deputy Sheriffs and staff who look after people in jails.

Economy

Agriculture is very important in Sonoma County, especially for growing grapes used in winemaking. The county has a mild climate and rich soil, which helps farmers grow many different plants and raise animals. Besides grapes, farmers also grow apples, vegetables, and raise dairy cows, chickens, and other livestock.

Winemaking is the biggest industry in Sonoma County. It started in 1850 and has grown to become very famous. The county has many vineyards and wineries, growing grape varieties like Chardonnay and Pinot noir. Dairy farming is also important, with many dairies producing milk, cheese, and yogurt. Other industries include poultry farming, fishing, and technology companies.

Politics

For much of the 20th century, Sonoma County often supported Republican leaders in big elections. Only a few Democrats won there during that time, like Woodrow Wilson in 1912, Franklin D. Roosevelt in 1932 and 1936, and Lyndon B. Johnson in 1964. But today, like much of the Bay Area, the county usually supports Democratic leaders. The last time a Republican won most votes here was Ronald Reagan in 1984.

On November 4, 2008, Sonoma County voted against a change that would have stopped same-sex marriages.

As of February 2025, there are over 300,000 people registered to vote in Sonoma County. More than half are registered with the Democratic party, while about one-fifth are registered Republicans, and many choose not to say which party they support. In every city and town in the county, there are more people registered with the Democratic party than with the Republican party.

Education

Sonoma County has many places for learning, from colleges to elementary schools. Some of the higher education schools include Empire College in Santa Rosa, Sonoma State University in Rohnert Park, and Santa Rosa Junior College.

The county also has many school districts for children in grades K-12. These include unified districts like Cotati-Rohnert Park Unified School District and Healdsburg Unified School District, as well as many elementary and secondary school districts. The Sonoma County Library system helps everyone with reading and learning, offering many books and resources for students and families.

Museums

Sonoma County has several interesting museums to explore. You can visit the Pacific Coast Air Museum to learn about airplanes, the Charles M. Schulz Museum in Santa Rosa dedicated to the famous cartoonist, the Museum of Sonoma County in Santa Rosa showcasing local history, and the Luther Burbank Home and Gardens in Santa Rosa to see beautiful gardens and learn about a famous plant expert.

Places of interest

Sonoma County has many special places to visit. You can explore natural beauty spots like Armstrong Redwoods State Reserve, Bodega Bay, and Sugarloaf Ridge State Park.

There are also interesting historical sites such as Fort Ross, a former Russian trading post, and Jack London State Historic Park where author Jack London once lived. Other fun places include Sonoma Raceway for racing fans and Sonoma TrainTown Railroad for train enthusiasts.

Populated places

Cities

Sonoma County has nine cities where many people live.

Census-designated places

These are places where people live but they are not cities:

• Bloomfield
• Bodega
• Bodega Bay
• Boyes Hot Springs
• Carmet
• Cazadero
• El Verano
• Eldridge
• Fetters Hot Springs-Agua Caliente
• Forestville
• Fulton
• Geyserville
• Glen Ellen
• Graton
• Guerneville
• Jenner
• Kenwood
• Larkfield-Wikiup
• Monte Rio
• Occidental
• Penngrove
• Roseland
• Salmon Creek
• Sea Ranch
• Sereno del Mar
• Sonoma State University
• Temelec
• Timber Cove
• Valley Ford

Other unincorporated places

These are smaller places where people live but they are not part of a city:

• Annapolis
• Asti
• Camp Meeker
• Carneros
• Duncans Mills
• Freestone
• The Geysers
• Guernewood Park
• Hacienda
• Kellogg
• Korbel
• Lakeville
• Lytton
• Mark West
• Mark West Springs
• Mercuryville
• Mesa Grande
• Rio Nido
• Schellville
• Stewarts Point
• Two Rock
• Venado
• Villa Grande
• Vineburg

Former townships

In the past, Sonoma County had special areas called townships.

At first, there were four townships. By 1880, there were 14 townships including:

• Analy
• Bodega
• Cloverdale
• Knight's Valley
• Mendocino
• Ocean
• Petaluma
• Redwood
• Russian River
• Salt Point
• Santa Rosa
• Sonoma
• Vallejo
• Washington

Population ranking

This list shows how many people live in different places in Sonoma County, based on information from the 2010 census.

† county seat

In popular culture

Main article: Film locations in Sonoma County, California

Film

Sonoma County’s beautiful landscapes and its closeness to San Francisco have made it a popular place for filming movies. Some of the very first movies made in the United States were filmed here, like Salomy Jane from 1914 and a Western from 1915 by Broncho Billy Anderson.

Many famous films were made in Sonoma County, including The Farmer's Daughter from 1947 with Joseph Cotten and Loretta Young. Two movies by Alfred Hitchcock, Shadow of a Doubt from 1943 and The Birds from 1963, were also filmed here. American Graffiti was mostly shot in the town of Petaluma.

Other films produced partially in Sonoma County include:

Other

Bliss, the default computer wallpaper for Microsoft's Windows XP, is a picture of a green hill and blue sky with clouds taken in Sonoma County in 1996 by Charles O'Rear. It is one of the most viewed photos in the world. The name of macOS Sonoma comes from Sonoma County.