The city, drawn from its own records

What you are looking at

The outlines are the city’s own building footprints, each drawn at the height measured over it from the air. The roof colours are read off aerial photography. The ground underneath is the city’s elevation data, and the coastline, the streets and the block outlines are published files as well.

The closest view stops where the file stops. Footprints are published on a one-metre grid, so at Street one metre is about two and a half pixels on screen. That closeness is the same on a phone as on a desktop; a wider window fits more of the city into the frame, drawn no finer.

What is missing

The city publishes what is standing today, so a building that was pulled down is in no file and can appear in no year. The Western Addition thins out towards 1960 on this map because the city cleared it, and what it cleared was never here to draw.

A building is drawn from the year the assessor gives it, in the shape it has now. Later additions and conversions are folded into that shape.

The decisions

They come from two record systems, 1906–2026 in all. {avol} scanned volumes of the Board of Supervisors’ minute books and the department annual reports, {aspan}, held by the Internet Archive; and {cfiles} minutes files the Clerk of the Board posts on sfbos.org, {cspan}, which no library holds. 94,427 of them land somewhere on this map. 40,498 name only a street the block fronts, and the panel keeps those apart from the ones that name the block itself. Another 18,432 name no place we could resolve, and are drawn nowhere at all.

Placement was checked against the {key} decisions that print their own block number, hiding that sentence from the join and scoring what it did without it — 3,043 of them were placed precisely enough to score, and 88.5% landed on the block the record named.

Where this comes from

None of it is our own survey. San Francisco’s open data portal publishes the buildings, the blocks, the streets and the ground they stand on. The scanned volumes are held by the Internet Archive, the minutes since 2016 are posted by the Clerk of the Board on sfbos.org, and the aerial photography the roof colours are read from is Esri’s. A few things are worked out from those files rather than published directly — the average roof colour of a block, for one — and the catalogue linked at the foot of this page says which, field by field.

• DataSF · 22 datasets
• FAA ↗ · 2 datasets
• FHWA ↗ · 2 datasets
• USGS ↗ · 2 datasets
• DataSF, from the California Department of Education · 1 dataset
• DataSF, from the National Center for Education Statistics, as of 2011 · 1 dataset
• this map's own authored landmark register · 1 dataset
• this repository — the name is authored, everything else is read · 1 dataset
• US Census ↗ · 1 dataset
• US Census Bureau ↗ · 1 dataset
• US National Park Service · 1 dataset
• Esri World Imagery
• NOAA NCEI ↗
• San Francisco Board of Supervisors
• San Francisco Board of Supervisors / DataSF