03/18/2011 07:20 pm ET Updated May 25, 2011

Habitats for Humanity

Review of Arrival City: How The Largest Migration In History Is Reshaping Our World. By Doug Saunders. Pantheon. 356 pp. $27.95

Immigration may well be the most important issue of our time. Between 2000 and 2050, according to journalist Doug Saunders, the cities of the world will absorb over three billion people, a majority of them migrants from farms and villages. By mid-century, more than 70% of the world's population will be urban, with enormous consequences for developed and developing countries.

In Arrival City, Saunders makes a compelling case that immigration can be a boon -- and not a threat -- to prosperity and political stability. Faced with shortages of low-skilled and semi-skilled workers and a surfeit of retirees, he points out, the United States, Europe, India, and China will, almost certainly, find themselves recruiting (and competing for) immigrants. Indeed, he adds, in one of many surprising - -and controversial -- findings in his book, that in Canada "chronically poor" immigrants often fare much better than those with university degrees.

Beautifully written and richly detailed, Arrival City provides the material to counter know-nothing claims about globalization, secure borders, amnesty, and immigration restriction.

Immigrants will thrive, he argues, only if governments attend to the arrival cities (ethnic districts that are also known as favelas, bustees, gecekondular, shantytowns, and slums) where newcomers congregate. Often ignored, "battered by violence, strangled by neglect and misunderstanding," these enclaves link immigrants to their originating village (sending people and money back and forth) and to the established city. Located, among other places, in Mumbai, in Kenya, near Chonqing, on the outskirts of Paris, and at the periphery of Los Angeles (Saunders has visited them all), arrival cities can provide "a purchase, however fragile, on the edge of the larger society, and give them a place to push themselves, and their children, further into the center, into acceptability, into connectedness."

Arrival cities, moreover, do not accelerate population growth. After villagers settle in, their fertility rates drops, by at least one child per family. Thanks to migration, the United Nations estimates, sometime around 2050 the population of the world will level off -- and sustainability may become a more manageable, though still daunting, problem.

Arrival cities are often characterized as incubators of crime, religious extremism, revolutionary violence, drug gangs, and terrorism. In Iran, the Ayatollah Khomeini, and in Venezuela, Hugo Chavez, used failing arrival cities "as fuel," sending inhabitants "inward to seize the political center of their nations."

Beneath the squalor, Saunders points out, lies a more complex reality. Snapshots cannot capture the paradox of successful gateway cities: the more successful they are, the higher their poverty rates will be. As residents get jobs, save money, and move within a generation to more affluent middle-class neighborhoods, they are replaced by new (and very poor) migrants. Los Angeles, for example, "flushes out at least a third of its population each decade," in an oft repeated cycle of "arrival, upward mobility, and exodus."

Nonetheless, Saunders emphasizes, immigrants are not likely to thrive on their own. Governments might begin by offering pathways to citizenship (making regularization "an option in advance"). This approach allowed Spain to add a half million immigrants to its tax rolls each year "without creating a marginalized class on the outskirts."

To build a thriving middle class and not an angry, outcast community, Saunders believes, government must make significant investments in the infrastructure of arrival cities. High on his list are schools ("the handholds for social mobility") attuned to the needs of immigrants; opportunities to own property (an important source of seed capital in the developing world), and start a business. Only government, Saunders reminds us, can provide garbage collection, paved roads, transportation (to a job outside of the ghetto), and street lighting (which makes "a tangible difference in both security and property value, at a low operating cost").

At the very moment when they are needed the most, Saunders reminds us, governments have adopted tight spending policies, turned to privatization, and succumbed to xenophobia. And even under more favorable economic conditions, we might add, politicians are not likely to spend significant amounts of tax-payers' money on "outsiders." Especially if they seem to give immigrants a "leg up" on the natives.

These days, it seems, in the United States and other democracies, citizens -- and their elected representatives -- are loath to look beyond the next quarterly report; unwilling to "invest" in human capital and infrastructure; and incapable of breaking through the political paralysis to implement policies, even when they are designed to address problems that just about everyone agrees are pressing.

In this context, then, we are not likely to approach, let alone achieve, Doug Saunders' aspiration of fashioning "the world's final century of urbanization" into a force of "lasting progress, an end to poverty, a more sustainable economy."

But we can do better than we're doing now: by entertaining and acting on the counter-intuitive proposition, advanced by Saunders, that, with some help from the collective "we," immigrants can help halt the shrinkage of the middle class - -and usher in a better future for all of our children and grandchildren.