925 Area Code: Concord, California

Northeast of San Francisco Bay, the 925 area code covers a band of inland communities organized around Concord, with the broader footprint stretching across central Contra Costa County and into the eastern Tri-Valley. Concord itself sits in a wide valley between Mount Diablo to the south and the Carquinez Strait to the north, and the surrounding 925 footprint runs through Walnut Creek, Pleasanton, Livermore, San Ramon, and Antioch — postwar suburban centers that filled in the cattle ranches and orchards as Bay Area commuting expanded eastward.

Records the directory has compiled for 925 numbers frequently include other California cities — Anaheim, Bakersfield, Chico, Daly City, and others. None of those are inside the 925 footprint. The pattern reflects California's standard high number mobility through porting, prior registration, and the public-record sources that link addresses across cities. The directory currently documents 483 distinct prefixes within 925 in detail, a working subset of the prefixes the code actually carries.

The most striking demographic feature of Concord and the broader 925 corridor is household income, which runs well above the US median — supported by Bay Area wage levels carried inland by commuters. Home values come in roughly two-and-a-half times the national figure, the city's median age sits a touch under the US reading, and the population places Concord among the larger inland Bay Area cities, a regional commercial center serving the surrounding Contra Costa communities.