There is something happening in many North American cities right now. We are starting to question the supremacy of zoning for only single-family homes.

This past summer, the state of Oregon passed policy requiring cities of 25,000 people or more to allow duplexes, triplexes, and fourplexes within their single-family home neighborhoods. Minneapolis is poised to do something similar with its Minneapolis 2040 plan (though it has been contentious). And, of course, here in Toronto we recently rolled out laneway suites all across the city. Small scale multi-family dwellings are also already permissible in some areas (though few are being built).

Some are calling this a YIMBY movement. But however you want to define it, it's an acknowledgement that, if the goal is to built up instead of out, perhaps it's time we look at the parts of our cities with the lowest population densities. I would also add that following my recent post on Paris vs. Vancouver, many seemed to gravitate (in the comments) toward the Parisian model -- even if it did result in over 50,000 people per square kilometer. Density, it would appear, is okay.

While positive, it remains to be seen whether these policy changes will result in a meaningful increase in housing supply. And a lot of that will come down to the details. As I have said before on the blog, the math can be challenging on these sorts of smaller projects, which is why you have smart people proposing things like an "inverse density" rule to help encourage more smaller scale development.

But as the saying goes, sometimes you need to crawl before you can walk. And, if nothing else, there's certainly symbolic value to what seems to be taking hold across North America right now.

Daniel Hertz of City Observatory recently published an interesting post talking about what makes American zoning unique compared to the rest of the world. It is based on the conclusions of a book published earlier this year called Zoned in the USA.

Here are 2 snippets that I liked from his post:

Hirt’s major claim is that what really sets American zoning apart is its orientation, explicit or implicit, to putting the single-family residential zone at the top of the hierarchy of urban land uses. Not only are single-family zones listed first in many zoning codes, but they make up significant pluralities, or even majorities, of total land area in most American cities. Interestingly, Hirt points out that this wasn’t necessarily true when zoning was first introduced: New York’s famous first zoning law didn’t even have a single-family zone at all.

As Hirt points out, Americans appear to be unique in believing that there is something so special about single-family homes that they must be protected from all other kinds of buildings and uses—even other homes, if those homes happen to share a wall. The