In the US, it's a combination of lack of building, increased materials costs, and (in places like California) government policies that block new construction.

In the US, it's a combination of lack of building, increased materials costs, and (in places like California) government policies that block new construction. Note that Trump's tariffs on Canadian lumber increased the cost of new construction by 20% over a period of a few months (the article mentions the cost of materials, but not the root cause, which was this tariff, and some climate disasters, like when the Texas storms took out 20% of global PVC production for a year or so). Biden has been aggressively increasing tariffs, so they are both directly to blame. The interest rate spike and high inflation were predicted by pretty much all economists when Trump decided to needlessly keep rates low during his first term, so blaming Biden never made much sense to me Anyway, lots of studies have been done looking for root causes for homelessness and unaffordable housing. Every theory I've heard (drugs, mental health, nice weather for tent encampments, joblessness, etc, etc) has been shot down by such studies except the idea that if you have fewer houses per capita, then you will have more homeless people and more expensive houses. Assuming global financial stuff changed radically but we didn't build more houses, where would these people with lots of money in the bank live, exactly? Also, wouldn't that cause the price of housing to increase (increased demand, constrained supply, and inflation from the increased money supply)? The graph you cite says the US has 0.4 houses per person. That means that, on average, we don't have enough houses for people that are single, couples without a live-in kid, or single parents. It goes on to say that 7% of US houses are vacant, but that wouldn't make up the gap. Also, many houses in the US are vacant because there are in places where the economy has dried up, and there aren't adequate utilities, schools, groceries, etc. Even if those houses were somehow renovated, many people would still be better off financially if they chose to live on the street instead of in those places.