Here is a study by three researchers out of California that asked Americans to predict the impact of a supply shock on various things, such as durable goods, commodities, labor, trade, and yes, housing.

For basically all of these items, people tended to answer correctly. Usually by a factor of at least two to one. In other words, when asked what reducing the supply of new cars would do to the prices of used cars, the majority of people responded saying that it would lead to an increase in prices.

However, when asked about the impact of a 10% increase in housing supply, about 40% said that it would cause prices and rents to rise. Only about a third believed they would fall (the correct answer). This is fascinating because it shows that housing seems to be an outlier. Most people don't have the same intuitive sense.

Why is this? Well, one commonly held belief is that building market-rate housing leads to gentrification, and that this ultimately leads to the displacement of existing residents. This might have been why some people responded saying that new housing will cause an increase in prices and rents. It'll lead to all housing going up.

However, there's research to support that this isn't the case. The problem isn't outward displacement following new market-rate housing. The greatest driver of gentrification is actually "exclusionary displacement", which is the inability of people to move into areas because of a lack of housing. (This study was based on 2010-2014 housing data from the UK.)

The thing about housing supply is that it relieves pressure across the entire market. Instead of a high-income person buying an old home to renovate (and causing outward displacement), they can instead choose to buy a new home (and not cause any outward displacement).

By doing this, they also leave behind a home that can then be absorbed by lower earners. One US study found that for every 100 new market-rate homes that are built, somewhere between 45 and 70 people move out of a below-median income neighborhood.

It is for reasons like these that, time and time again, increased housing supply has been shown to moderate home prices and rents (see above regarding Minneapolis and the Midwest as a whole). So if you're worried about the cost of housing, the answer is to build more. And if you're worried about gentrification, the answer is also to build more.

Our intuitions are telling us that this is true for most things. But for whatever reason, housing feels different. It's not, though.

Source: The charts and studies in this post are from this great FT article by John Burn-Murdoch.

There is a very common story that plays out in cities. It starts with an area that has seen disinvestment and is probably a little seedy and/or dangerous . This creates an environment where rents and real estate as a whole are relatively inexpensive. New, cool and creative businesses start to move in (attracted by said inexpensiveness) and the area begins to turn around. Eventually it becomes suitable for institutional-type investors, and this ultimately leads to everything becoming expensive as a result of demand outstripping supply. Gentrification complete.

The great irony of this story is that you sometimes, or oftentimes, lose the very things that made the area cool and interesting in the first place. Here is an example from Miami:

The result has been a property speculation boom that, when combined with the city's relatively low wages, put many businesses and residents on the street. Asking rents for industrial space, for instance, went up by 53 percent in the last year alone. Nobody can afford to buy, let alone rent, adequate space for a music venue because so much land has been snapped up by outside investors with a predilection for grand, "world-class urban" designs. 

And for some areas, it is arguably the result of a careful and deliberate plan that was put in place nearly two decades ago:

Teele's commissioner district in the early 2000s included both Park West and the historically Black neighborhood of Overtown. At the turn of the millennium the area was blighted and crime-ridden thanks to years of racist, regressive policy decisions from segregation to redlining. His plan was simple but incredibly effective. He spearheaded a campaign to revitalize the area by granting a limited number of 24-hour liquor licenses to clubs like Space. Dozens of venues rose up on and around 11th Street, including vast, multi-room clubs like Metropolis, live venues like Studio A and Grand Central, and more intimate spots like Vagabond. Sporadic police raids also gave the area a druggy, dangerous reputation, inadvertently raising its allure. 

This reoccurring arc has led some people to conclude that cities and/or areas seem to want to follow a kind of binary outcome: they're either dying or they're too successful. Why can't we just have urban homeostasis? I don't think this is necessarily always the case. Cities go through cycles just like any other market. I also know that it's complicated. But I do feel strongly that we need to be mindful that part of what makes cities such wonderful places is that they are factories for new ideas and creativity.

I can't remember when or exactly how he said it, but YouTuber Casey Neistat once described New York City as an incredible island (Manhattan?) where misfits from all over the world come to do whatever the hell they want. And that part of the reason for this is that nobody cares what you do, because everyone is just so damn busy. You could certainly argue that New York isn't what it used to be. But the lesson here remains the same: Cities are at their best when they allow humans to create, build, experiment, and express themselves.

And oftentimes a great place for that is in a space that nobody else wants.

One criticism that you will sometimes hear about development is that the construction of new housing can spur gentrification. The thinking, I think, is that when you create new market-rate housing, richer people will then move in and the area will begin (or continue) its ascent upwards.

If on the other hand, one were to just stop developing new housing, then the neighborhood would remain stable and static and the fear of gentrification would simply go away. But the flaw in this line of thinking is that it assumes no infill development equals some sort of urban homeostasis.

Cities are constantly changing. The reality is that what we are talking about, particularly in the case of low-rise single-family areas, is that we want the physical character of neighborhoods to remain more or less the same. But what happens on the inside is whatever.

Here's an example:

What you are seeing here are 4 electricity meters, meaning that at some point this structure housed 4 separate homes. But 3 of the 4 meters have now been removed, which presumably means that this structure has been converted (probably back) to a single-family home. So this is 4 homes being reduced to 1.

I don't know what this place looks like on the outside, but I'm going to guess that not much has changed in terms of its physical character. It probably looks about the same. But this is still gentrification; it is still an example of a neighborhood moving upmarket.

The irony is that we tend to be generally okay with this change. We are okay with reducing the number of homes in a neighborhood so long as it happens in a largely inconspicuous and convenient way. But what we are (sometimes) not okay with is increasing the number of homes in a neighborhood. Apparently that creates too much pressure on the existing housing stock.