415 Area Code: San Francisco, California

San Francisco is the primary city of the 415 area code, which has been associated with the city since the dawn of direct distance dialing and remains tightly tied to it after several rounds of metropolitan numbering reorganization. The city occupies the tip of a peninsula bounded by the Pacific on one side and the bay on the other; its hills, fog patterns, neighborhood boundaries, and dense low-rise housing stock give it a built environment that differs sharply from most US cities. The 415 designation today serves the city of San Francisco itself along with portions of Marin County to the north across the Golden Gate.

The directory's records linked to 415 numbers often surface other California cities — Anaheim, Bakersfield, Chico, Concord, and many more. None of those sit inside 415's footprint. Their recurrence is a function of California's high inter-city number mobility and of the routine cross-linkage patterns that show up in public-record sources. We document 651 distinct prefixes within 415 in detail, which is a working subset of the prefix population the code actually carries.

San Francisco's housing market drives much of its demographic distinctiveness. Typical home values run more than four times the US median — among the very highest readings of any major American city — and household incomes sit comfortably above national figures, reflecting both the cost-of-living premium and the city's concentration of finance, legal, and technology employment. Population is in the mid–800,000 range, and median age skews close to the US reading.