Triumph of the City: How Our Greatest Invention Makes Us Richer, Smarter, Greener, Healthier and Happier. By Edward Glaeser.Penguin; 336 pages; $29.95.To be published in Britain by Macmillan in March; £25. Buy from Amazon.com, Amazon.co.uk

“THE world isn't flat,” writes Edward Glaeser, “it's paved.” At any rate, most of the places where people prefer to dwell are paved. More than half of humanity now lives in cities, and every month 5m people move from the countryside to a city somewhere in the developing world.

For Mr Glaeser, a Harvard economist who grew up in Manhattan, this is a happy prospect. He calls cities “our species' greatest invention”: proximity makes people more inventive, as bright minds feed off one another; more productive, as scale gives rise to finer degrees of specialisation; and kinder to the planet, as city-dwellers are more likely to go by foot, bus or train than the car-slaves of suburbia and the sticks. He builds a strong case, too, for town-dwelling, drawing on his own research as well as that of other observers of urban life. And although liberally sprinkled with statistics, “Triumph of the City” is no dry work. Mr Glaeser writes lucidly and spares his readers the equations of his trade. This is popular economics of the best sort.

What makes some cities succeed while others fail? Successful places have in common the ability to attract people and to enable them to collaborate. Yet Mr Glaeser also says they are not like Tolstoy's happy families: those that thrive, thrive in their own ways. Thus Tokyo is a national seat of political and financial power. Singapore embodies a peculiar mix of the free market, state-led industrialisation and paternalism. The well-educated citizenries of Boston, Milan, Minneapolis and New York have found new sources of prosperity when old ones ran out.

Detroit is the book's prime example of decline. In the 19th century it had the right, vibrant combination: educated people and a mass of small businesses. By the late 20th century it was a one-industry town, dominated by three huge companies employing hundreds of thousands of workers with too few skills. Between 1950 and 2008 its population shrank by 58%. It also fell victim to the “edifice complex”, the belief that new office blocks, sports arenas and transport systems alone can stop the rot. Other cities, such as Leipzig and Youngstown, Ohio, are held up as examples of cities accepting shrinkage and finding better use for land than empty houses. Detroit now seems to be following.

Mr Glaeser is likely to raise hackles in three areas. The first is urban poverty in the developing world. He can see the misery of a slum in Kolkata, Lagos or Rio de Janeiro as easily as anyone else, but believes that “there's a lot to like about urban poverty” because it beats the rural kind. Cities attract the poor with the promise of a better lot than the countryside offers. About three-quarters of Lagos's people have access to safe drinking water; the Nigerian average is less than 30%. Rural West Bengal's poverty rate is twice Kolkata's.

The second is the height of buildings. Mr Glaeser likes them tall—and it's not just the Manhattanite in him speaking. He likes low-rise neighbourhoods, too, but points out that restrictions on height are also restrictions on the supply of space, which push up the prices of housing and offices. That suits those who own property already, but hurts those who might otherwise move in, and hence perhaps the city as a whole. And tall buildings do not have to be in soulless streets.

So Mr Glaeser wonders, heretically, whether central Paris might have benefited from a few skyscrapers. He certainly believes that his hometown should preserve fewer old buildings. And he thinks that cities in developing countries should build up rather than out. New downtown developments in Mumbai, he says, should rise to at least 40 storeys.

The third, related, area is sprawl, which is promoted, especially in America, by flawed policies nationally and locally. Living out of town may feel green, but it isn't. Americans live too far apart, drive too much and walk too little. The tax- deductibility of mortgage interest encourages people to buy houses rather than rent flats, buy bigger properties rather than smaller ones and therefore to spread out. Minimum plot sizes keep folk out of, say, Marin County, California. He sees it as an indictment of planning that spreading Houston has “done a better job of providing affordable housing than all of the progressive reformers on America's East and West coasts.” Mr Glaeser hopes, for the planet's sake, that China and India choose density over sprawl and public transit over the car. If his own country set a better example, there might be more chance of persuading them.

Cities need wise government above all else, and they get it too rarely. That is one reason why, from Paris in 1789 to Cairo in 2011, they are sources of political upheaval as well as economic advance. The reader may wonder if Mumbai really would be better off as a city of high-rise slums rather than low-rise ones. But Mr Glaeser clearly believes that hell isn't other people; heaven's more like it, for all our faults. He's right, and he says it well.