The relationship between car ownership and urban density is a fairly intuitive one. Below are two charts from a study by Francis Ostermeijer, Hans Koster, Jos van Ommeren, and Victor Nielsen, showing how urban density is inversely correlated with car ownership. In other words, the more people with cars, the less dense that a particular place is likely to be.

But there's an interesting chicken-and-egg question here. Does Atlanta, which is near the bottom right in the above chart, have a lot of cars because it wasn't dense enough to support other modes of transport, or did the prevalence of cars in Atlanta cause the city to spread out and become less dense? And that is exactly what the above researchers set out to determine.

To do this, they started by looking at the presence of commercial car manufacturers in the above geographies in the 1920s. One of the things they found was that having a car manufacturer in your city at this time appears to have had no effect on population density. But over the long run, rising car ownership seems to have had a sizeable effect on reducing population densities in those places.

The conclusion they draw from this is the title of this post: cars have made cities less compact, rather than low population densities causing people to go out and buy more cars. This makes some sense to me because cities were doing just fine before we invented cars. But like all transportation innovations that allow us to move faster over longer distances, the car encouraged decentralization.

There are, of course, all sorts of possible implications for a finding like this. But the authors specifically mention developing countries where car ownership may still be relatively low. This is something to be mindful of because if you put most people into cars, history strongly suggests that it will impact the kind of city that you end up building.

Chart: Cars make cities less compact

This recent article by Brookings is a good reminder of the all too important link between land use policies/patterns and GHG emissions. Because electric vehicles are cool and all, but they're still not as efficient as just walking around and/or taking transit.

As has been argued before on this blog, we need to not only electrify our transport network, but we also need to change how we get around. And probably the best way to encourage a modal shift, is to plan and build our cities differently. Something that is simple, but not easy.

It also turns out that people who live in multi-family buildings tend to consume less energy (on a per capita basis) than those in single-family houses. So there are numerous benefits to encouraging denser housing on top of transit and within mixed-used communities.

With all of this in mind, here are some interesting charts from the above Brookings article.

The relationship between car ownership and urban density is a fairly intuitive one. Below are two charts from a study by Francis Ostermeijer, Hans Koster, Jos van Ommeren, and Victor Nielsen, showing how urban density is inversely correlated with car ownership. In other words, the more people with cars, the less dense that a particular place is likely to be.

But there's an interesting chicken-and-egg question here. Does Atlanta, which is near the bottom right in the above chart, have a lot of cars because it wasn't dense enough to support other modes of transport, or did the prevalence of cars in Atlanta cause the city to spread out and become less dense? And that is exactly what the above researchers set out to determine.

To do this, they started by looking at the presence of commercial car manufacturers in the above geographies in the 1920s. One of the things they found was that having a car manufacturer in your city at this time appears to have had no effect on population density. But over the long run, rising car ownership seems to have had a sizeable effect on reducing population densities in those places.

The conclusion they draw from this is the title of this post: cars have made cities less compact, rather than low population densities causing people to go out and buy more cars. This makes some sense to me because cities were doing just fine before we invented cars. But like all transportation innovations that allow us to move faster over longer distances, the car encouraged decentralization.

There are, of course, all sorts of possible implications for a finding like this. But the authors specifically mention developing countries where car ownership may still be relatively low. This is something to be mindful of because if you put most people into cars, history strongly suggests that it will impact the kind of city that you end up building.

Chart: Cars make cities less compact

This recent article by Brookings is a good reminder of the all too important link between land use policies/patterns and GHG emissions. Because electric vehicles are cool and all, but they're still not as efficient as just walking around and/or taking transit.

As has been argued before on this blog, we need to not only electrify our transport network, but we also need to change how we get around. And probably the best way to encourage a modal shift, is to plan and build our cities differently. Something that is simple, but not easy.

It also turns out that people who live in multi-family buildings tend to consume less energy (on a per capita basis) than those in single-family houses. So there are numerous benefits to encouraging denser housing on top of transit and within mixed-used communities.

With all of this in mind, here are some interesting charts from the above Brookings article.