North Dakota, South Dakota, eastern Montana and northern Minnesota are the coldest places in the continental US and the houses mostly tend to be cheap and flimsy. Houses in California seemed to be much more robust, actually. Build quality probably has a lot more to do with local building codes.

I think it depends more on the year the house was built. Newer houses seem to be built really cheaply, while ones from 50+ years ago here are fairly solid.

Proximity to a fault line is also a major factor (influencing local building codes, as well as common sense and economics).

Flimsy houses built 50+ years ago likely don't exist anymore.

My landlord will likely be fairly distressed with this news. ;)

I think it has to be more than 50 years old. More like 70. Most of the houses around here look like they were built in the 60s, 70s and 80s and are not great.