It's not number of houses, it's number of houses where people want to live.

"house prices would not be increasing in areas of population decline" -> the causation could be running backwards: a family of 2 (maybe 2 retired people with accumulated wealth) can outcompete with a young family of 4 for the same unit, that drives prices up and population down. I'm not saying this is the case, but decreasing population not being associated with decreasing housing prices does not mean that increasing housing prices is not caused by housing scarcity

After thirty years of house prices rising astronomically, you can't appeal to "speculation" any more. People are speculating because the underlying scarcity makes prices sure to rise.

I think if you look closely at "population down, house prices up" you will find normal supply-and-demand stories like "population down, houses down even more" or "population down (downtown), prices up (suburbs)".

You can't look at the cost of a house out of context. If you look at Flint, Michigan it's actually one of the most expensive places in the country if you account for average income in that area. Absolute cost needs to be normalized by income in the area. The housing is actually very expensive if you do this type of calculation. We saw an example of under supply during COVID. Housing prices in "underpriced" areas increased during COVID because regions with no real economy saw people moving there with the high out of state salaries. Those areas didn't have enough supply. Now that remote work is less prevalent, those places are having their costs go down but the Bay Area is seeing skyrocketing costs. We are able to measure the effects of supply and demand pretty clearly due to COVID.

Speculation is known to have an effect, but not nearly as much as an effect as under supply. Blackrock THEMSELVES published a paper that the reason their investments are working is due to the low development of housing. Their whole strategy is reliant on NIMBYism and people's lack of understanding of the housing market.

Anyone with 60 seconds of free time can trivially see that your claims hold no water.

Simply Google for cities/areas with declining population, choose one, look up average housing prices there over the last 10 years or so, see how they've changed, correct the figures for inflation, and you'll see that in almost all cases inflation-adjusted prices are lower today in those places than they were 10 years ago.

Not necessarily.

House occupancy laws also have a role here - some of the living arrangements that ended up in higher density in the past are illegal today, forcing population decline in a given area (which is not necessarily equivalent to _demand_ decline)

There's no question that underbuilding is the largest factor here. You can look at construction vs. population over time (it's well below historical standards). Or available home vacancy rates. Or notice that the number of households is increasing faster than the number of homes. Or look at the various models, which show a 2 million-4 million shortfall in homes.

That aside, housing prices are reasonable in much of the country. Where population is stagnant or declining, they are generally reasonable.

are these areas with declining populations and rising housing prices increasing the number of houses? it could be that the population declines because no one can afford to live there however it's still a desirable area so prices remain high. cities like Austin are seeing reduction in housing prices despite population increase due to construction of new housing.

If they were unaffordable they would not be selling. Don't underestimate just how much money people can conjure up. Most parents don't want to be buried with their money Egyptian pharaoh style.

How do you separate speculation from legitimate price increases? If the houses are overpriced due to speculation, why isn't someone building Alternatives and undercutting them? This implies that there is either a real increase in value, a manufactur bottleneck, or both