Making bay land was estimated to cost $330,000 an acre. Land zoned for single-family houses in San Francisco County averages $24 million
A 1955 state estimate for 23,000 acres looks like a bargain next to the average price of land for single-family houses in San Francisco County.
The Works in Progress Newsletter · Why San Francisco isn’t biggerIn 1955, California estimated it could reclaim ground along the western shore of San Francisco Bay for about $330,000 an acre in 2025 dollars, while an acre of land zoned for single-family houses in San Francisco County now averages about $24 million, more than 70 times as much.
The comparison comes from a 1955 estimate by the California Division of Water Resources for reclaiming 23,000 acres along the western shore of the bay, adjusted to 2025 dollars, set against the current average county price for land zoned for single-family houses.
The contrast holds beyond San Francisco itself. Even the Bay Area's lowest-priced county averages more than $330,000 an acre. Since 1990, downtown land has risen sharply in worth even as suburbs kept expanding, reaching levels that could cover the cost of making new ground even where suburban land is plentiful.
Questions people ask
Why doesn't San Francisco just fill part of the bay and build?
Laws passed in the 1970s, especially the National Environmental Policy Act and the Clean Water Act, require extensive environmental reviews and federal permits for filling wetlands and bays. Those reviews now often run thousands of pages and can take years or decades, which makes large reclamation projects slow and expensive to attempt.
How is new land actually made from shallow water?
Builders typically wall off a shallow area with a dike or seawall, then pump in sand, mud, or rock dredged from nearby waters until the surface sits above sea level. The fill must then settle and be compacted before roads and buildings can go on top. It is ordinary dredging and construction work, but done at very large scale.
Is San Francisco Bay shallow enough to fill?
Much of it is very shallow. About two thirds of the bay is shallower than 20 feet, and parts of the South Bay near Silicon Valley are less than six feet deep.