But it is also the age of migration alarm, as European ships patrol African coasts to intercept human smugglers and new fences are planned along the Rio Grande. Countries that want migrant muscle and brains also want more border control. Many of them see illegal migrants as a security threat, especially in a terrorist age, and worry that large-scale migration, even when legal, can undercut wages, require costly services and subject national identities to bonfires of religious and cultural conflict.

The stakes can be seen here in Mindelo, a semicircle of barren hillsides that gaze out at the only sign of natural life, a beckoning sea. In a country with little rain and a history of famine, migration began as a necessity and became part of the civic DNA. You can dine at Café Portugal, drink at the Argentina bar and stroll Avenida da Holanda.

Yet Holland — the Netherlands — now requires would-be migrants to pass a test on Dutch language and culture. Other countries have raised the cost of visa applications, discouraged applicants by requiring them to travel to the Cape Verdean capital, Praia, and placed new penalties on employers who hire illegal immigrants. While the Netherlands has long been a favorite destination for residents of this island, a Cape Verdean song now warns that “Holland belongs to the Dutch.”

Watch out

Because they can make you go back swimming

And you’ll get home with seaweed in your teeth

Mindelo, Cape Verde’s second-largest city, contains 63,000 people and about as many variations on the migrant’s tale. On the hillside neighborhood of Monte Sessego, Maria Cruz, 70, beams at the living room suite her son sent from Rotterdam. Out toward the airport, Stenio da Luz dos Reis, 17, studies Dutch and hopes to join his mother in the Netherlands. Down by the beach, Orlando Cruz, 46, stares at vacant tables. He fell off a ladder in New Jersey and used the insurance money to start a hotel and restaurant, which are now nearly empty.

As construction racket fills her half-finished house, Evanilda Lopes, 27, speaks freely about the fraudulent papers that got her to the Netherlands. As he hustles change for his H.I.V. medication, Manuel Gomes, 41, is equally frank about the crimes that got him deported from Providence, R.I. He moved there as a child and grew up wild — selling drugs, stealing cars and burglarizing homes. Now like hundreds of others deported here from the United States, he finds himself a man without a country, exiled to a world no less foreign for having been the place of his birth.

“You have a Cape Verdean here who would cut his right arm off to go back,” said Mr. Gomes, who lives in a one-room hovel without running water or electricity.