Silicon Valley

Related Category: Miscellaneous U.S. Geography

an industrial region, approximately 20 mi (32 km) long, in the Santa Clara Valley between Palo Alto and San Jose, mainly in Santa Clara and San Mateo counties, W central Calif., where many computer manufacturing and design companies are located. Computer-software and other high-technology industries are also there. The name derives from high-purity silicon used in making the semiconductors used in computers.