Sprawl is how much of the US provides new housing, and so it's interesting to ask the opposite question: Which cities are actually building new housing in walkable neighborhoods? Here is a study published this week by the Terner Center for Housing Innovation at UC Berkeley that looked at exactly this. What they did was divide all US neighborhoods into five categories based on vehicle miles traveled (VMT) per resident in 2023.
The categories:
Very Low VMT - 12 miles per person per day
Low VMT - 17.3 miles per person per day
Mid VMT - 21 miles per person per day
High VMT - 25.5 miles per person per day
Very High VMT - 37.5 miles per person day
These seem like oddly specific distances, but it's what they used to sort new housing supply. Here's all of the US:
Since the 1950s, new home production in very low VMT neighborhoods has generally been declining. Most of the lower VMT stuff was built before the 1940s, which is why New York City is so walkable and its chart looks like this:
Most newer cities do not build in this way. In fact, based on this study, there are only five large metro areas in the US that have (1) built at least 15% of their total housing since 2000 (meaning, they're a younger city) and (2) built at least 40% of their homes over the last decade in lower-VMT neighborhoods (very low and low).
These metro regions are:
This is not that many cities. At the same time, is it even the right benchmark to be aspiring to? "Lower VMT" just means you don't need to drive as much as you might in other neighborhoods. But it doesn't necessarily mean that you live in an amenity-rich and walkable community. What about the new homes being built in neighborhoods where people don't need a car at all? How many of these exist?
Very few, I'm sure.
Cover photo by Jo Heubeck & Domi Pfenninger on Unsplash
In 1620, an Englishman by the name of Edmund Gunter invented a land surveying device known as Gunter's chain. As the name suggests, it was an actual chain (see above). Each chain contained 100 links and, when fully extended, it measured 66 feet.
This was a monumental innovation as it greatly simplified land surveying and made it a lot easier to measure out acres -- especially if you maybe weren't great with math. So it is perhaps no surprise that this simple device forever changed our cities.
But first, here's the only math you need to know:
Number of chains x number of chains / 10 = number of acres
For example:
A lot measuring 66 feet by 66 feet would mean it has an area of 4,356 square feet, or 0.1 acres (1 acre = 43,560 square feet). It would also mean that this lot measures 1 chain by 1 chain, or 1 square chain. Take 1 square chain and divide it by 10, and you arrive at the same 0.1 acres.
Similarly, a lot measuring 660 feet by 660 feet would mean it has an area of 435,600 square feet, or 10 acres. Using Gunter's chain, this lot is 10 chains by 10 chains, which equals 100 square chains. Divide 100 square chains by 10 and you arrive at the same 10 acres.
Put differently, 1 acre equals 10 square chains in Gunter's system.
Because of its simplicity and utility, the chain became a statutory unit of measurement in England by the 1670s. And as a result, it spread throughout the British Empire, meaning it started to influence how new cities were being planned and laid out.
Let's look at the example of Salt Lake City.
We have spoken before about the city's famously large blocks. They have the dubious distinction of being the largest in the US. But what you may not have noticed is that the typical SLC block measures exactly 660 feet x 660 feet. Its typical streets are also 132 feet wide.
This is because of Gunter's chain. These are 10-chain x 10-chain blocks and 2-chain streets.
The same is true of other cities. Looking on the other end of the spectrum, Portland's compact street grid is comprised of blocks that measure 198 feet x 198 feet. These are, in other words, 3-chain blocks. Its typical streets are also 33 feet wide. So half-chain streets.
Units of measurement have a lasting way of influencing how we plan and design things. This is true at small scales and it's also true of our cities. In tomorrow's post, we'll look more closely at Salt Lake City's street grid and what it does to walkability.
Back in 2017, Portland, Oregon enacted new inclusionary zoning policies mandating that all new residential projects with 20 or more units must deliver a specified amount of affordable housing. Early accounts, by people like Joe Cortright of City Observatory, suggested that the market was reacting to this new requirement as you might expect. Developers rushed to get new applications onto the books and then there was a drop off in new housing supply.
Now that it's been a couple more years, it is perhaps worth checking in on Portland. Cortright did that in the fall of last year and the housing numbers are continuing to fall. From 2019 to 2020, new multi-unit housing permits in Portland fell by more than 60%. I really don't know the Portland market and so it's hard for me to comment on whether it is solely the fault of IZ, but there was a peak in 2017 and now housing permits are down significantly. However, they were also down significantly during the financial crisis. It'll of course be interesting to see how this plays out over a longer time horizon.
That said, a similar market response was recently reported in another Portland -- Portland, Maine. In 2020, the city implemented a "Green New Deal" that stipulated, among other things, that all new residential developments with 10+ units would be subject to their new IZ policies. It has only been just over a year, but according to the city's planning department, there were 756 new housing units on the books in 2020 prior to the new IZ policies. And since then, that figure has dropped to 139 new housing units. This is admittedly a small market and a relatively short time horizon, but it is still a data point.
As many of you know, I struggle with inclusionary zoning. Maybe it's confirmation bias, but I just haven't been able to find much data suggesting that it can meaningfully increase overall housing supply and the supply of new affordable units. So if any of you are aware of some good case studies outlining successful examples, please share them in the comment section below.