houses of the size typical decades ago can no longer be built
houses of the size typical decades ago can no longer be built
When you add over-wide roads laid out in pedestrian-hostile patterns, additional zoning restrictions on commercial buildings, etc., the end result in many places developed in the past few decades (including almost every recently developed neighborhood in the USA) is to depress density, increase per-unit housing prices, force most residents to travel by car, etc.
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Edit: your other comments indicate you live in San Jose. It seems that minimum home size is not regulated there, but there are many other exclusionary features of San Jose zoning. https://www.spur.org/sites/default/files/publications_pdfs/S...
Most municipalities in the US has some kind of minimum dwelling size, sometimes varying by zone. They can be anywhere from a few hundred square feet to about a thousand square feet (or occasionally bigger). Like other local laws, they vary widely in the details.
You can check local municipal zoning codes for whatever specific community you are interested in. San Jose is one of the rare places which apparently does not have such a rule. Though sometimes building codes enforce minimum sizes when zoning laws per se do not – I don’t care enough to go read through the San Jose building codes.
For more general discussion, if you do a web search for “minimum house size” you will get millions of results.