Silicon Valley is in the cultural, commercial, and financial center of North California.
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.
