ARRIVAL CITY

Doug Saunders, Pantheon, 356 pages, $27.95

Around the world, most immigrants, along with untold domestic migrants, leave rural communities and head to urban areas. These migrants settle in "arrival cities," working-class immigrant neighborhoods at the margins of bigger urban destinations. Cities from San Francisco to Sao Paulo sprang up thanks, in large part, to rural-to-urban migration.

In his new book, "Arrival City: How the Largest Migration in History Is Reshaping Our World," Doug Saunders analyzes the impact of urban migration on global demographics and social mobility. For the most part, this is a journalist's well-researched account of the people and places he has visited. Rather than viewing the neighborhoods where immigrant communities form as "immigrant ghettos" or "ethnic enclaves," Saunders would have us examine them as "arrival cities."

However, the book meanders between past, present and future in an effort to elevate the phrase "arrival city" to one of timeless import. Saunders chose a most worthy topic and has a wealth of experience to draw on, but he over-argues his case by trying to write a book that heralds the end of history -- migration has always been, and likely always will be, a part of the human experience, but Saunders gives no reason to think it more defining of this moment in history than, say, climate change, war, economic collapse and so on.

The major contribution of "Arrival City" is a call to take seriously the needs of immigrant communities. As he points out, "Our debates about immigration are too often concerned with questions of what should happen, what ought to be allowed; we devote far too little to planning for what will occur." Immigrant arrival cities, "in order to achieve social mobility," need a "strong and assertive government willing to spend heavily on this transition."

In the United States, at least, governments seem all too willing to spend heavily on immigration enforcement even as funding and political will are in short supply when it comes to investing in the future middle class. No one book is likely to transform American immigration policy, but "Arrival City" is worth a read.

SAN FRANCISCO CHRONICLE