Sonoma County comprises the Santa Rosa, CA Metropolitan Statistical Area, which is also included in the San Jose-San Francisco-Oakland, CA Combined Statistical Area. It is the northwestern county in the nine-county San Francisco Bay Area region.
Sonoma is the southwestern county and largest producer of California's Wine Country region, which also includes Napa, Mendocino, and Lake counties. It has 13 approved American Viticultural Areas and over 250 wineries. In 2002, Sonoma County ranked as the 32nd county in the United States in agricultural production. As early as 1920, Sonoma County was ranked as the eighth most agriculturally productive US county and a leading producer of hops, grapes, prunes, apples, and dairy and poultry products, largely due to the extent of available, fertile agricultural land in addition to the abundance of high quality irrigation water. More than 7.4 million tourists visit each year, spending more than $1 billion in 2006. Sonoma County is the home of Sonoma State University and Santa Rosa Junior College.
Sonoma County is home to several Native American tribes. By the 1830s, European settlement had set a new direction that would prove to radically alter the course of land use and resource management of this region. As of 2007, Sonoma County has rich agricultural land, albeit now largely divided between two nearly monocultural uses: grapes and pasturage. The voters have twice approved open space initiatives that have provided funding for public acquisition of natural areas, preserving forested areas, coastal habitat, and other open space.
The Pomo, Coast Miwok and Wappo peoples were the earliest human settlers of Sonoma County, between 8000 and 5000 BC, effectively living within the natural carrying capacity of the land. Archaeological evidence of these First people includes a number of occurrences of rock carvings, especially in southern Sonoma County; these carvings often take the form of Pecked curvilinear nucleated design. Spaniards, Russians, and other Europeans claimed and settled in the county from the late 16th to mid 19th century, seeking timber, fur, and farmland.
The Russians were the first newcomers to establish a permanent foothold in Sonoma County, with the Russian-American Company establishing Fort Ross on the Sonoma Coast in 1812. This settlement and its outlying Russian settlements came to include a population of several hundred Russian and Aleut settlers and a stockaded fort with artillery. However, the Russians abandoned it in 1841 and sold the fort to John Sutter, settler and Mexican land grantee of Sacramento.
The Mission San Francisco Solano, founded in 1823 as the last and northernmost of 21 California missions, is in the present City of Sonoma, at the northern end of El Camino Real. El Presidio de Sonoma, or Sonoma Barracks (part of Spain's Fourth Military District), was established in 1836 by Comandante General Mariano Guadalupe Vallejo. His duties included keeping an eye on the Russian traders at Fort Ross, secularizing the Mission, maintaining cooperation with the Native Americans of the entire region, and doling out the lands for large estates and ranches. The City of Sonoma was the site of the Bear Flag Revolt in 1846.
Sonoma was one of the original counties formed when California became a state in 1850, with its county seat originally the town of Sonoma. However, by the early 1850s, the town of Sonoma had declined in importance in terms of both commerce and population, its county buildings were crumbling, and it was relatively remote. As a result, elements in the newer, rapidly growing towns of Petaluma, Santa Rosa, and Healdsburg began vying to move the county seat to their towns. The dispute ultimately was between the bigger, richer commercial town of Petaluma and the more centrally located, growing agricultural center of Santa Rosa. The fate was decided following an election for the state legislature in which James Bennett of Santa Rosa defeated Joseph Hooker of Sonoma and introduced a bill that ultimately resulted in Santa Rosa being confirmed as county seat in 1854. Allegedly, several Santa Rosans, not caring to wait, decided to take action and, one night, rode down the Sonoma Valley to Sonoma, took the county seals and records, and brought them to Santa Rosa. Some of the county's land was annexed from Mendocino County between 1850 and 1860.
Early post-1847 settlement and development focused primarily on the city of Sonoma, then the region's sole town and a common transit and resting point in overland travel between the region and Sacramento and the gold fields to the east. However, after 1850, a settlement that soon became the city of Petaluma began to grow naturally near the farthest navigable point inland up the Petaluma River. Originally a hunting camp used to obtain game to sell in other markest, by 1854 Petaluma had grown into a bustling center of trade, taking advantage of its position in the river near a region of highly productive agricultural land that was being settled. Soon, other inland towns, notably Santa Rosa and Healdsburg began to develop similarly due to their locations along riparian areas in prime agricultural flatland. However, their development initially lagged behind Petaluma which, until the arrival of railroads in the 1860s, remained the primary commercial, transit, and break-of-bulk point for people and goods in the region. After the arrival of the San Francisco and North Pacific Railroad in 1870, Santa Rosa began to boom, soon equalling and then surpassing Petaluma as the region's population and commercial center. The railroad bypassed Petaluma for southern connections to ferries of San Francisco Bay.
Six nations have claimed Sonoma County from 1542 to the present:
Sonoma County was severely shaken by the 1906 San Francisco earthquake. The displacements along the faultline averaged .