Area Code 707 History:
Area code 707 was put into service. Area code 707 was created from a split of area code 415.
Counties in California within area code 707 include:
Del Norte County, Humboldt County, Lake County, Marin County, Mendocino County, Napa County, Solano County, Sonoma County, and Trinity County.
Major cities or places in California within area code 707 include:
Area code 707 serves most of northwest California including the larger cities and communities of Benicia, Eureka, Fairfield, Napa, Petaluma, Rohnert Park, Santa Rosa, Suisun City, Vacaville, Vallejo, and Windsor, in addition to many smaller communities within the area code 707 service area.