Silicon Valley is not really a valley, though it did originally harken back to the Santa Clara Valley’s geography. The towns and cities which are included in Silicon Valley are primarily in Santa Clara County (by far the largest Silicon Valley city is San Jose), with San Mateo County also having a number of areas, with little snippets of Santa Cruz County and Alameda County.
While San Jose is the largest city in Silicon Valley, the epicenter of the region is probably Palo Alto – Mountain View – Sunnyvale.
This is an amorphous area. If you asked 10 different real estate agents, you might get 5 or 6 different answers, but I believe the list below would be agreed upon by most.
It is important to note that San Francisco is NOT in Silicon Valley. Many reporters get this wrong and report on Silicon Valley with stories out of SF. The regions are certainly related, and there are high tech companies in The City but they are distinct.
A list of which cities are part of Silicon Valley
In Santa Clara County (most of the county) – also known as the South Bay
- Gilroy – possibly
- Los Altos
- Los Altos Hills
- Los Gatos
- Los Gatos Mountains (not incorporated) – possibly
- Monte Sereno
- Morgan Hill
- Mountain View
- Palo Alto
- San Jose
- Santa Clara
In San Mateo County (bayside areas) – on The Peninsula
- East Palo Alto
- Foster city
- Menlo Park
- Portola Valley
- Redwood City
- Redwood Shores
- San Carlos
- San Mateo
In Alameda County – in the East Bay
- Possibly Newark, Hayward
In Santa Cruz County – not part of the San Francisco Bay Area (9 counties), but part of the Monterey Bay Area and the Central Coast
- Scotts Valley
- possibly Santa Cruz & Santa Cruz Mountains
Where is Silicon Valley?