Cape Verde, the tiny island nation off Africa’s west coast, is a virtual microcosm of global migration.

In Cape Verde, the number of people who have left almost equals the numbers who remain and just about everyone has a close relative living in Europe or North America.

Migrant remittance money is vital to the local economy. Migrant votes can sway local politics and new migrant departures split parents from children.

The emotional intensity of the Cape Verdean experience is summed up in the island’s most famous song ‘Soledad’ – or ‘longing’ – and the nation is a study in how migration is reshaping many societies across the globe.

In a country with little rain, a history of famine and a population of only 500,000, migration began as a necessity and has become part of the national psyche.

In Mindelo, Cape Verde’s second largest city, you can dine at the Café Portugal, drink at the Argentina bar and stroll the Avenida de Holanda.

Across the globe an estimated 200 million people live outside the country of their birth, and they help support a swathe of the developing world as big, if not bigger.

Migrants sent home about $300 billion last year — nearly three times the world’s foreign aid budgets combined. Those sums are building houses, educating children and seeding small businesses, and they have made migration central to discussions about how to help the global poor.

But it is also the age of migration alarm, as many nations – including Australia – have introduced rigorous border protection regimes to intercept human smugglers.

New fences are planned along the Rio Grande on the US-Mexico border. 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.