Government Code section 23138

The boundaries of San Francisco city and county are as follows:
Beginning at the southwest corner, being the northwest corner of San Mateo, in the Pacific Ocean, on the extension of northern line of T. 3 S., of Mount Diablo base; thence northerly along the Pacific Coast, to its point of intersection with the westerly extension of the low-water line on the northern side of the entrance to San Francisco Bay, being the southwest corner of Marin and northwest corner of San Francisco; thence easterly, through Point Bonita and Point Cavallo, to the most southeastern point of Angel Island, all on the line of Marin; thence northerly, along the easterly line of Marin, to the northwest point of Golden Rock (also known as Red Rock), being a common corner of Marin, Contra Costa, and San Francisco; thence due southeast four and one-half statute miles to a point established as the corner common to Contra Costa, Alameda, and San Francisco; thence southeasterly, on the western line of Alameda County to a point on the north line of T. 3 S., R. 4 W., M D. B. & M.; thence westerly on the township lines and an extension thereof to the place of beginning. The islands known as the Farralones (Farallons) are a part of said city and county.

Source: Section 23138, https://leginfo.­legislature.­ca.­gov/faces/codes_displaySection.­xhtml?lawCode=GOV§ionNum=23138.­ (updated Jan. 1, 1947; accessed Jun. 25, 2025).

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Verified:
Jun. 25, 2025

§ 23138's source at ca​.gov