Solano County is a county located in the U.S. state of California, about halfway between San Francisco and Sacramento. It is officially one of the nine San Francisco Bay Area counties, and one of four North Bay counties. The county's population was reported by the U.S. Census to be 413,344 in 2010. The county seat is Fairfield and the largest city is Vallejo.
Solano County was one of the original counties of California, created in 1850 at the time of statehood.
At the request of General Mariano Guadalupe Vallejo, the county derives its name directly from an Indian Chief, Chief Solano of the Suisun people, a Native American tribe of the region and Vallejo's close ally. Chief Solano at one time led the tribes between the Petaluma River and the Sacramento River. The chief was also called Sem-Yeto, which signifies "brave or fierce hand." The Chief was given the Spanish name Francisco Solano during baptism at the Catholic Mission, and is named after the Spanish Franciscan missionary, Father Francisco Solano. "Solano" is a common surname in the north of Spain, especially in Navarra, Zaragoza and La Rioja.
Travis Air Force Base is located just east of Fairfield.