The North Bay is a subregion of the San Francisco Bay Area, in California, United States. It is by far the least populous and least urbanized part of the Bay Area. It consists of Marin, Sonoma, Napa, and Solano counties. It is, unusually for a major metropolitan area, still highly agricultural in character. The internationally famous California wine country (primarily consisting of growing areas in Sonoma County and the Napa Valley) is located in the North Bay. The region's largest city, Santa Rosa, is situated on the Santa Rosa Plain in the heart of Sonoma County. Historically, the area is also known for dairy farming. Although the growth of the wine industry has slowly edged out some of the dairy industry, it is still common to see cows grazing on the hillsides of Sonoma County in particular. Solano County is the notable exception to this pattern, with exurban development occurring at a rapid pace on former pastureland surrounding Vacaville and Fairfield. The growth of these two cities is largely a function of their proximity to both San Francisco and Sacramento, although some North Bay residents commute all the way to San Mateo or Santa Clara counties.