Claim: Silicon Valley is in the cultural, commercial, and financial center of North California.
Evidence: The region has expanded to include the southern half of the San Francisco Peninsula in San Mateo County , and southern portions of the East Bay in Alameda County.
San Francisco -LRB- initials SF -RRB- -LRB- -LSB- sæn_frənˈsɪskoʊ -RSB- , Spanish for Saint Francis ; Spanish : -LSB- san franˈsisko -RSB- -RRB- , officially the City and County of San Francisco , is the cultural , commercial , and financial center of Northern California.