Firefighters stopped the 1906 fire from crossing 20th Street, which kept it out of the rest of the Mission District. More than a century later, that line still matters for anyone reading a building age map.
San Francisco has one of the oldest housing stocks among large U.S. counties. The median home was built in 1948, and about 44% of homes date from before 1940.
Key takeaways
Median home age in San Francisco is 1948. The U.S. median is 1981.
Only Brooklyn and Suffolk County, Massachusetts have older housing among the 100 largest counties.
About 44% of homes predate 1940, and only about a third were built after 1969.
The 1906 earthquake and fire destroyed more than 80% of the city.
The median home was built in 1948, which is the third-oldest date among the 100 largest U.S. counties. Brooklyn (1946) and Suffolk County (1947) come first. Nearby Bay Area counties are much younger, and the national median is 1981. The figures come from 2023 American Community Survey estimates, where residents report the year they believe their building went up, so they are approximate.
Area
Median year built
Brooklyn, N.Y.
1946
Suffolk County, Mass.
1947
San Francisco
1948
San Mateo County
1966
Alameda County
1969
United States
1981
Why are so many buildings in San Francisco from before 1940?
Much of the housing had to be rebuilt after 1906, when the earthquake and fire destroyed more than 80% of the city, roughly 25,000 buildings across 490 blocks. Some counts run higher. Dennis Smith’s history puts the toll at 28,188 buildings.
The rebuilding did not carry on past mid-century. Planning experts cited by the Chronicle point to state and local laws from the 1960s and 1970s that slowed development. Only about a third of the city’s homes went up after 1969, against 44% in Los Angeles County.
