San Francisco, CA

ZIP code 94109 is assigned to San Francisco, CA, and falls within City and County of San Francisco County. Like every US postal code, it began as a mail-routing device rather than a geographic boundary — the US Postal Service groups delivery routes under a single code so carriers and sorting equipment can process mail efficiently. Today it also serves as a practical shorthand for the area itself: roughly 54,397 people live inside it.

At 50,414 residents per square mile spread over 1.079 square miles, 94109 reads as a dense urban area. It is a populous postal code, and density shapes almost everything else on this page — how people get to work, whether they own or rent, and what housing costs.

Household earnings run above the national median. At $112,201, 94109 sits comfortably in the upper half, ahead of 89% of them. The US median for comparison is $70,109. Bear in mind that median income describes the midpoint household, not the average — it is not pulled upward by a handful of very high earners the way a mean would be.

Housing in 94109 costs far above the national median. A typical home is valued at $1,390,000 against a US median of $207,500, and median gross rent runs $2,172 a month. This is firmly renter territory — 81.9% of occupied homes are rented, a pattern typical of city centres, student areas and neighbourhoods with a lot of apartment stock.

The building stock is dominated by mid-sized apartment buildings, which account for 54.9% of housing units here. The median construction year is 1938, making the housing here largely pre-war.

The population skews broadly in line with the national age profile, with a median age of 38.9 against 42 nationally. Households average just 1.71 people, and 57.6% consist of one person living alone — a signature of areas with a lot of studio and one-bedroom stock.

Getting to work takes 31.9 minutes on average one way. The dominant mode is worked from home at 28.1% of workers, while 21.1% take public transit, 24.0% walk, 28.1% work from home. Commute patterns are one of the better proxies for how a place actually functions day to day.

Beyond addressing mail, 94109 does a lot of quiet administrative work. Retailers use it to calculate shipping and sales tax at checkout. Insurers use it to set premiums, since risk profiles vary geographically. Employers and marketers use it to define service areas. Government agencies use it to route benefits and organise reporting. If you have ever been asked for a postal code by a form that clearly does not intend to send you anything, this is why.

For anyone weighing a move, 94109 offers a compact profile of San Francisco: 54,397 residents, a median household income of $112,201, 65.2% of adults holding a bachelor's degree or higher, and an unemployment rate of 6.2%. A handful of figures like these answer more relocation questions than most neighbourhood guides do.

One caution worth repeating: a postal code is not a neighbourhood. 94109 may cover parts of several distinct areas, and a single neighbourhood in San Francisco may be split across more than one code. Boundaries also shift as USPS adjusts delivery routes. Treat the figures here as describing a delivery area, which is what they actually measure.