Silicon Valley is in a state.
Oakland [ ˈoʊklənd ] is the largest city and the county seat of Alameda County , California , United States . The Santa Clara Valley runs south-southeast from the southern end of San Francisco Bay in Northern California in the United States . Silicon Valley is a nickname for the southern portion of the San Francisco Bay Area , in the northern part of the U.S. state of California . The `` valley '' in its name refers to the Santa Clara Valley in Santa Clara County , which includes the city of San Jose and surrounding cities and towns , where the region has been traditionally centered .