The perfect city?

Ed Glaeser on the perfect city, the demons of density and what makes cities work.

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Across our series so far we’ve been asking big questions about fast-growing cities: how to build enough housing, how to make land legible, how to pay for infrastructure, how to prevent crime from taking root, and how to ensure young people see cities as ladders, not dead ends.

This week on Ideas in Development, Ed Glaeser, professor of economics at Harvard and one of the world's leading urban economists, joins us to think about how these fit together.

Ed was quick to pour cold water on utopian thinking about perfect cities.

“The road to urban dysfunction is paved by dreams of urban perfection, and… frequently more incremental improvements to city life are a wiser course to follow rather than thinking that you’re gonna get it exactly right.”

He does, though, has a clear theory of what cities are for. They exist to enable possibilities for ordinary people that we would never find on our own. Whether the year is 1500 or 2050, whether the city is in sub-Saharan Africa or sixteenth-century Europe, the work of urban government generally boils down to three things. Get those right, and a city can become an escalator out of poverty. Get them wrong, and the demons of density will come back to bite you.

Safety, mobility, education – and a fourth thing

Glaeser’s three foundations are safety, mobility and education.

Cities exist “to bring people close to one another, to enable us to work together in different ways, to buy, to sell, to borrow ideas, to communicate.”

Each of the three foundations is a precondition for that to actually happen: law because density without law is just easier predation; mobility because proximity is meaningless if you cannot reach across it; and education because learning is what people in dense places trade with each other.

The metrics he would track to understand how cities are doing follow naturally. For safety, homicides (which remains the only metric broadly comparable across time and space) supplemented by victimisation surveys, with one particularly diagnostic question for the developing world: have you been held up by the police? Fear of police abuse, Ed notes, is a particularly useful sign that something’s gone badly wrong with the provision of safety.

For mobility, travel speeds (the kind Gilles Duranton’s team can now extract from Google street maps), augmented by cell phone data on how poor and rich residents actually mix across neighbourhoods and workplaces. For education, years of schooling, plus test scores like PISA.

But there is a fourth metric that matters at least as much, because it captures whether the other three are doing their job. Cities are both fun places to be rich but often less intolerable places to be poor.

This inequality is “only tolerable when cities are providing escalators out of poverty into prosperity.”

The thing to measure, then, is upward mobility itself: the dynamics of individual wealth over time. A city that is failing on safety, education or mobility will eventually show up here, in the gap between what poor residents arrive with and what they leave with.

Infrastructure, incentives, institutions

A recurring theme of our conversation is that urbanists who focus on infrastructure alone are only focusing on part of the problem. Ed tells the story of nineteenth-century New York, which he grew up being told was a tale of engineering triumphalism: the Croton Aqueduct dispelled cholera and yellow fever from a fetid early-1800s city. But the truth was less heroic. For 25 years after the aqueduct opened, New York continued to have cholera outbreaks, because building the pipes did not solve the problem. Even with free hydrants, the water was heavy to carry, and poor residents were unwilling to pay for private connections. Mortality only fell once the city imposed fines on tenement owners who refused to connect.

“It wasn’t until the city started imposing fines on tenement owners who didn’t connect to the water system… that you really saw the cholera rates decline.”

The same dynamic shows up in his more recent work on Lusaka, where there is a strong correlation between how customers pay for water and how long water breaks stay broken. When customers pay by the litre, the company has a sharp incentive to fix breaks fast. When customers pay by the month, as they often do in poorer areas, repairs drag.

“If they don’t get fixed, the water company won’t get paid, so the water company fixes those things.”

The pipes are necessary. The incentives that surround them decide whether the pipes actually deliver water.

Then institutions, after the infrastructure itself, and incentives, represent the last I. There are many options available (direct public provision, parastatals, non-profits, fully private), and Ed cautions against being ideological, and remaining practical based on local context. But he does have one strong piece of advice on parastatals.

Only choose that route, he says, “if you can actually get someone who will lead this entity who has an international reputation that can be lost.”

Without that kind of figurehead, a parastatal is mostly a layer of plausible deniability that lets the mayor blame someone else for failures.

Bus good, train bad

“Forty years of transportation economics at Harvard can be boiled down to four words. Bus good, train bad.”

Trains lock cities into enormously expensive, fixed investments that struggle to adapt, while buses, BRT systems, or even better-organised jitneys (privately operated minibuses) are flexible, cheap and serve poorer riders.

Within that, two more specific recommendations stand out. First, procurement discipline. The United States pays roughly $1.05 million for an electric bus that can be bought from Hyundai for $350,000, because American transit agencies insist on bespoke specifications.

“Basically any developing world city that’s customising their buses in the fashion of US transit agencies is making a huge mistake.”

So buy at scale, from large global producers.

Second, road repaving. With Gabriel Kreindler and Lindsay Currier, Ed has used US Uber data to show that in eight of eleven cities studied, there is no correlation between how rough a road is and whether it gets repaved next.

“We are repaving the rough roads just as frequently as we are repaving the smooth roads.”

A simple targeting rule, fix the bumpiest first, is sitting in plain sight.

Capacity eats policy as a light afternoon snack

The biggest constraint on actually doing any of this, Ed argues, is not knowledge but capacity. Doing his best management consultant impression, he says:

“in local government, capacity eats policy as a light afternoon snack.”

A mayor has 100 things hitting their desk every day and perhaps five people who will reliably do what they ask. The size of the civil service is misleading. He recalls former Rome mayor Ignazio Marino, who had over 100 projects he wanted to pursue and only two people who were actually willing to do anything that he told them to do.

That has implications for how academics work with mayors. Trying to redirect a leader’s scarce capacity toward priorities they did not choose is “a fool’s errand on a grand scale.”

Influencing policy, in Ed’s experience leading the IGC’s Cities That Work initiative, almost always depends on personal relationships with city leadership. White papers help, particularly because the people who read them often sit in finance ministries and can pose harder questions back to local governments, but they are not a substitute for a mayor or a chief of staff who actually wants to engage.

He names some of the leaders he has been most impressed by: Geordin Hill-Lewis in Cape Town, Jennifer Musisi in Kampala, Enrique Peñalosa and Claudia López in Bogotá, and Yvonne Aki-Sawyerr in Freetown.

The skill they share is balancing technocratic substance with political legitimacy. Comparing Michael Bloomberg and Tom Menino in the United States, Ed notes that Menino could build an innovation district and convince ordinary Bostonians it was for them; Bloomberg could do exactly the same thing in New York and be accused of catering to his rich tech friends.

Plan the public realm, free the private one

On the perennial question of how much to plan, Ed splits the city in two. Public spaces, the road network, the basic infrastructure, the strategy for how mobility will evolve, need real planning. Private spaces, by contrast, do better with minimal planning, beyond bans on genuinely noxious uses. Ed contrasts post-war Tokyo, which rebuilt with light public direction and a well-designed land-readjustment process that allowed small owners to pool plots into larger structures, with post-war Beirut, where heavy central planning produced a polished downtown shopping district whose benefits to ordinary Lebanese citizens are hard to identify.

“I’m certainly on the side of the spectrum that favours maximal planning for the public spaces that are needed to provide mobility and to deal with sanitation and all those things, but fairly minimal control over what private individuals can do with their property”

That same instinct shapes his three priorities for sub-Saharan Africa over the next decade. Public health infrastructure first, with water at the centre – and not just the pipes, but the incentives and last-mile fines that get people connected. Education second, including the vocational skills that wrap around schooling, with humility about which interventions actually work. And third, mobility done well: smarter buses, better procurement, and congestion pricing built in from the start of any new road, on the model of Singapore in 1975.

“There’s no way to actually make streets smooth without actually charging people for the use of those streets.”

Politically, putting a charge on a road that used to be free is brutal. Putting one on a road that did not exist yesterday is not.

What unites all of Ed’s thinking a refusal to mystify cities. The demons of density – disease, crime, congestion – are ubiquitous, faced by Julius Caesar’s Rome and medieval London just as much as by Lagos or Lusaka today. The tools that work against them are mostly known. The harder problem is building enough state capacity, and enough trust between leaders and citizens, to use those tools well.