408 Area Code: San Jose, California

Anchored on San Jose, the 408 area code covers the heart of Silicon Valley — the South Bay floor stretching from the southern reaches of San Francisco Bay down through the Santa Clara Valley into the foothills of the Diablo Range. San Jose itself is California's third-largest city by population and the nominal capital of the technology cluster that has reshaped the region over the past several decades; the city's pre-tech economy was built on orchards and canneries, and the older neighborhoods still carry traces of that period beneath the office parks and engineering campuses that now dominate the landscape. The 408 designation, part of the North American Numbering Plan, has carried Silicon Valley numbers since the early 1960s.

A long catalog of California cities — Anaheim, Bakersfield, Chico, Concord, and others — turns up in the directory's records associated with 408 numbers. None of those are inside the 408 footprint. The pattern reflects the unusually high mobility of California numbers and the way porting, prior registration, and address linkages route records across area-code lines. We currently hold detailed records on 666 distinct prefixes within 408, which represents the directory's working coverage; the underlying prefix allocation runs higher.

The most striking demographic feature of San Jose is its income profile. Median household income sits dramatically above the national figure — closer to twice the US reading — reflecting the wage premium of the surrounding tech industry. Home values run several multiples of the US median, and the city's median age is close to the country's. Population places San Jose among the largest cities in California.