In 1973, 580,000 mobile homes (or manufactured home as they are now called) shipped in the United States. This represented about 50% of the number of single-family housing starts that year, and about 22% of total housing starts. So they represented a significant chunk of the overall housing supply.

But following the collapse of the US housing market in 1974, an interesting thing happened. Manufactured homes never managed to reclaim their position in the stack. See above chart. Brian Potter, author of Construction Physics, puts forward a number of possible explanations for this, over here.

Some have speculated that it was the result of new code changes that ended up increasing costs. Some have speculated that it was because of a new requirement to include a steel chassis on the bottom of every home, which also increased costs, but more importantly stigmatized manufactured homes. It made them seem transient, whereas previously they were installed on permanent foundations.

There are also some theories that manufactured home production was harder hit during the economic downturn given that they had more fixed plant costs (compared to site-built homes with their variable labor costs).

But Brian's current working theory is that it comes down to capital flows. Manufactured homes tend to cater to lower-income buyers and so supply, as the argument goes, has largely depended on "lax lending" practices being made available to them.

I'm not so sure that this is the only reason though. For one thing, multi-family housing starts have followed a somewhat similar trajectory to manufactured homes. We've certainly seen an increase in supply over the last decade, but we've never gotten back to that early 1970's peak.

And so I wonder: How much of this is actually just the result of the single-family home hegemony? This is arguably what the market has historically wanted (look at the split pre-1973 in the above chart), and so perhaps we simply refocused our attention there and worked to make this housing type as accessible as possible to the masses.

Chart via Brian Potter

There's a lot of debate within urbanist circles about whether or not supply alone can solve or at least mitigate housing affordability concerns. Richard Florida and others will say that, while beneficial, increasing supply isn't the be all end all. We need to be building affordable housing.

Edward Glaeser, Joseph Gyourko, and others have, on the other hand, argued that middle-income housing is a supply problem and that low-income housing is quite simply a demand-side problem, which could be solved through things like a housing voucher program.

In other words, the cost of housing isn't necessarily the problem, it's the low income levels. One of the benefits of supplementing people's incomes is that it empowers mobility. People can then move to where there are jobs, as opposed to being tied to a specific neighborhood or city.

But this debate is arguably just about the extent of the supply benefits. Intuitively, it makes sense to try and match new housing supply with demand and economic growth. But how far can that take us, particularly in high demand and high productivity cities?

Glaeser (Harvard) and Gyourko (Penn) have a relatively recent paper out called, The Economic Implications of Housing Supply, which looks at, among other things, the "implicit tax" imposed on development as a result of land use restrictions and other supply constraints.

Here are two excerpts:

We will argue that the rise in housing wealth is concentrated in the major coastal markets that have high prices relative to minimum production costs, and it is concentrated among the richest members of the older cohorts—that is, on those who already owned homes several decades ago, before binding constraints on new housing construction were imposed.

But in a democratic system where the rules for building and land use are largely determined by existing homeowners, development projects face a considerable disadvantage, especially since many of the potential beneficiaries of a new project do not have a place to live in the jurisdiction when possibilities for reducing regulation and expanding the supply of housing are debated.

If you're interested in this topic (and sufficiently nerdy), you can download a PDF copy of the paper here.

Photo by chuttersnap on Unsplash