Silicon Valley is a region in California.
Oakland [ ˈoʊklənd ] is the largest city and the county seat of Alameda County , California , United States . San Francisco ( initials SF ) ( [ sæn_frənˈsɪskoʊ ] , Spanish for Saint Francis ; Spanish : [ san franˈsisko ] ) , officially the City and County of San Francisco , is the cultural , commercial , and financial center of Northern California . The Santa Clara Valley runs south-southeast from the southern end of San Francisco Bay in Northern California in the United States . Silicon Valley . As more high-tech companies were established across the Santa Clara Valley , and then north towards the Bay Area 's two other major cities , San Francisco and Oakland , the `` Silicon Valley '' name eventually came to refer to all high-tech businesses in the region .