A funny thing happened to urban planning in the early 20th century. As cities industrialised, their centres became denser and denser. And, as residents became wealthier, it seemed like a good idea to push outwards, making cities less densely populated by building up new communities on their fringes. Getting around these more dispersed suburbs wasn’t a problem, though, thanks to century’s greatest innovation: the car. 

So urban planners accepted, and even celebrated this development. As Le Corbusier once commented

The automobile is a new development with enormous consequences for the large city. The city is not ready for it… I tell you straight: a city made for speed is made for success.

But then, gradually, it became apparent that we’d made a huge mistake. Suburbs don’t make the city less dense during the day, when everyone is at work – especially not if all those suburbanites use their cars to get into the city’s centre. What’s more, suburban sprawl is, by definition, a pretty wasteful use of land. 

Now, we have an actual number to put on the adverse effects of sprawl. A new report from LSE estimates that in the US alone, sprawl costs the country in the region of $1trn a year. 

It’s worth saying that again: One. Trillion. Dollars. Every. Year.

The report defines sprawl as “dispersed, segregated, automobile-oriented, urban-fringe development”; as its opposite, it uses “smart growth”, which it defnies as “compact, mixed, multi-modal development”.  It estimates that the former uses up 60-80 per cent more land than the latter, and increases motor travel by 20-60 per cent.

Here are a few more things which are contributing to that $1trn a year:

  • Land filled with sprawl can’t be used as farmland or parkland, which can have a knock-on effect on food production;
  • It makes life harder for walkers, cyclists, and those who can’t afford a car, reducing economic activity;
  • Public transport networks, where they exist, must spread further, which costs more;
  • Public health and fitness tends to be lower, which costs more, too;
  • More driving leads to more traffic, accidents and pollution, all of which, yes, cost more. The report says that sprawling areas tend to have up to five times the traffic fatalities of “smart growth” communities.

Of course, sprawl has some benefits, especially for the people that live there: more space, less pollution, and better bang for their property buck. But the report notes that, while $625bn of the costs are borne by areas of sprawl themselves yearly, $400bn is borne by those outside it. In other words, everyone is paying for a better quality of life for those who reap the benefits.

The report also contains a few graphs which compellingly highlight the impact of all this. This cheery chart, for example, stacks up the economic impacts of car use:

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While this graph plots the number of road miles per 1,000 residents against the urban density of a given area: 

And here’s a chart showing space required for different kinds of travel mode:

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(More on cars’ space-hungry selfishness here.)

And finally, here’s a morbid one on traffic deaths in cities:

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Fatalities are far lower in compact cities – but it’s worth noting that affluence seems to have a pretty big impact, too. 

Now we’ve lectured you about getting rid of all your cars (seriously, get rid of all your cars), how do we get out of the mess sprawl has created?  

The report recommends two things. First, improved planning and zoning policies which forefront “smart”, compact growth: that is, which emphasise mixed communities, public transport and dense building. But there’s also retrospective work we can do on cities which are already sprawling, such as invest in new rail infrastructure and promote its use, plus reduce parking minimums. Onwards and inwards, folks. 

All visualisations taken from “Analysis of Public Policies That Unintentionally Encourage and Subsidize Urban Sprawl”, LSE, 2015.