[seanmcdirmid]

If demand picks up because supply increases, you will reach the previous equilibrium even with more supply. It isn’t rocket science, there is a price people are willing to pay to live in SD, and the market will keep gravitating to that price unless demand is somehow limited. The price people are willing to pay can even increase as density makes brings in things (eg culture, job opportunities) that make the city more desirable (eg see Hong Kong).

[darksaints]

At the levels of density seen in Paris, San Diego could house 16 million people. That's city proper. The metro area could house 226 million people.

You're gonna have to do a lot better job convincing me that 16 million people would move to San Diego if they just built more housing. Let alone 226 million.

[seanmcdirmid]

Twist do you think happens to every city that has reached 16 million people? Did they become more popular or less? Given that I’ve lived in a city of that size, my answer will differ from yours (they become more expensive, not less).

I’m confused on why you think paris is affordable and San Diego metro could somehow have enough water to grow to 220 million. The nearest comparison I can think of is south China Bay Area population (87 million), and if you think that those cities are affordable…I’m guessing we really have to agree to disagree.

[Dylan16807]

> Twist do you think happens to every city that has reached 16 million people?

It's not about the exact number, it's that one city is not going to 10x in population from getting the price of housing down to "still a city but not skyrocketing".

> I’m confused on why you think paris is affordable

Compared to San Diego, it does seem to be significantly more affordable, and mainly because of rent.

> and San Diego metro could somehow have enough water

The most expensive source of water, desalination, should be under $1 per day per person. And there's probably better options.

> to grow to 220 million.

That number is a silly number to explain density, not a proposal.

> and if you think that those cities are affordable…

No, the only comparison point was Paris, and the density of Paris.

[seanmcdirmid]

There is no way for San Diego to grow that fast overnight anyways. If it grows gradually, and it’s still desirable, that will attract more jobs and more people eventually, the city won’t become more affordable (long term) until it stops attracting new residents. Otherwise, new housing simply provides temporary relief while the city grows.

Paris is a good example, I think, of a city expensive by French standards. My point was that if your theory is you can build to affordable, there should be at least one example on the planet where that actually worked (even Tokyo is considered expensive by Japanese standards).

[Dylan16807]

> the city won’t become more affordable (long term) until it stops attracting new residents

I really hope we don't have indefinite large amounts of US population growth. And if we mostly stabilize the population, then it only takes a few 16M cities to absorb all the demand and make the relief permanent.

> Paris is a good example, I think, of a city expensive by French standards. My point was that if your theory is you can build to affordable, there should be at least one example on the planet where that actually worked (even Tokyo is considered expensive by Japanese standards).

Then consider this particular argument not that you can build to a nebulously defined "affordable", but that you can build to "San Diego has between 100% and 1000% of its current population with rent 40% lower than it is right now".

[seanmcdirmid]

> I really hope we don't have indefinite large amounts of US population growth.

You don't need indefinite growth. People generally want to live in a few cities; e.g. they don't really want to live in Toledo, they want to live in San Deigo. So you just have to let people live where they want to live, not where they have to lvie.

> Then consider this particular argument not that you can build to a nebulously defined "affordable", but that you can build to "San Diego has between 100% and 1000% of its current population with rent 40% lower than it is right now".

That has literally never happened before and I don't see how it will happen first in San Diego. Mega cities get more expensive, not cheaper, as they grow, since the concentration of human capital and jobs make it even more valuable to live there.

[darksaints]

San Diego would be a very popular city at lower prices, but simply put there isn't enough population in the US to even think that demand could grow anywhere close to those levels. It would take a 50 year long gold rush, draining of other American cities, etc. The fastest growing city in modern history, Shenzen, grew 6000% in 30 years, and it could only do so because China simultaneously had the highest population growth in the world and the highest urbanization rate in the world.

At some point, demand is saturated, and it takes an extremely delusional belief that demand can perpetually grow so that prices never drop. We have proof in the article that prices can drop with even moderately fast construction rates. Keep going.

[LudwigNagasena]

Yet the rent in Paris is still too high for an average French resident; and while rent is lower than in San Diego, the price of an apartment is higher. And, of course, median salary in San Diego is far higher than in Paris.

[ProfessorLayton]

>Yet the rent in Paris is still too high for an average French resident

It's obviously not just about more housing, but more housing per capita.

3% of the French population lives in Paris proper, and roughly 20% in the metropolitan area compared with 0.42% in San Diego and ~1% in San Diego MSA [1].

More hosing will help Paris along with San Diego to put downward pressure on prices.

[1] Wikipedia

[someperson]

There a lot of desirable areas in a country and a fixed amount of people.

The equilibrium between demand and supply has the supply curve impacted by a whole host of policy choices.

Eg housing is impacted by cost of permitting, regulations, cost of materials and labor etc.

All of these things can be improved by policy.

There's a strong argument that especially infrastructure but housing should be built with people on work visas.

[seanmcdirmid]

Water is the primary limiter on city population sizes in the west. I wouldn’t be surprised if San Diego wasn’t at its limit already with respect to water resources, but I haven’t looked into it. Desalination could improve that.

If we could have Chinese work crews come in and build housing, especially 30 story concrete towers that are popular in Asia, we could build fairly cheaply, that isn’t really the limitation (it’s easier to solve than getting water to those new units for expanded population).

[littlexsparkee]

San Diego in fact has a surfeit that it's looking at selling off

https://www.nytimes.com/2026/04/17/climate/san-diego-water-s...

[someperson]

They thought Vegas was at it's limit years ago, but no they found efficiency upon efficiency.

[verteu]

No, this is a false belief known as supply skepticism: https://scholar.google.com/scholar?hl=en&as_sdt=0%2C5&q=supp...

[LudwigNagasena]

Weird title for a paper that argues that "Government intervention is critical to ensure that supply is added at prices affordable to a range of incomes". I would personally classify that position as "supply skepticism".

[tptacek]

Supply increased, rents declined.

[seanmcdirmid]

Short term. Long term the market will change to equilibrium. If you are buying, just lock in lower housing prices now. If you are renting without rent control, you get one or two years of reasonable rates and then it will go nuts again.

[nostrebored]

This is an obviously farcical belief.

If everywhere built more housing do you think the price of housing would go up? Where are these people bringing up housing prices coming from?

[seanmcdirmid]

Buffalo has 50% as much housing now as it did at its peak, since demand dropped and housing was just razed rather than maintained. There are lots and lots of cities in the USA that aren’t San Diego, LA, SF, Portland, Seattle, NYC, Boston, … and they have plenty of supply that there is no demand for. You can buy a house for cheap in Toledo. For some reason, people would rather pay $3000/month to live in San Diego than $700/month to live in Buffalo or Toledo. It shouldn’t be a mystery why.

I lived in Beijing for 9 years so I get a different perspective. But ya, the market for people who want to live in Beijing rather than Chengde or Langfang is surprisingly vast, and Beijing has a resident system to prevent at will migrations.

[bombcar]

Housing prices always go up (they seem to believe this)

Houses can be built (this seems obvious)

Ergo, we can remove the national debt by building between 59 million and 121 million houses (depending on if you count the value of the land there).