In the historical museum on Ellis Island, just off Manhattan, there are sepia-tinted pictures of refugees from European countries who passed through its examination halls to escape repression and hunger in the Old World. One can listen to scratchy recordings and read fading letters from immigrants detailing the horrors they left behind and their hopes for a better life.
Today, at the beginning of the 21st century, these heart-rending stories of misery, hunger and death are still being enacted all over the globe. With the disparity between the rich and poor sections of the world growing, there are now an estimated 150 million migrants worldwide at any one time, of whom 15 million to 30 million are classified as "irregular", according to a recent study by the International Organisation for Migration (IOM). There are currently believed to be more than 90 million migrant workers and their families living in a country other than their own.
On China's border with North Korea, where conditions are reminiscent of the Famine, I have talked to refugees who saw their relatives die of hunger. One of the most harrowing scenes I witnessed as a reporter was of terrified East Timorese fleeing from murderous soldiers and militiamen. It is hard to forget the look of despair in the faces of Javanese settlers I saw fleeing in trucks from intimidation in Aceh, or in the eyes of a young Salvadorian caught by a US immigration patrol on the US-Mexican border near San Diego, or in the weather-beaten faces of Mongolian herders whose livelihood was wiped out by drought and cold.
But I have also come across many migrants who are beneficiaries of the new global economy, such as the Irish software designer who made a fortune in Tokyo or the Corsican couple who established a French restaurant in Ulan Bataar.
Many such people are following traditional migration patterns. The Irish, Chinese, Jews, Armenians, Arabs and Italians have for centuries sought to find a livelihood in host countries around the world and today they still do.
Others have always migrated within defined regions of the world, like the traders and store keepers of Sulawesi who are to be found in many parts of Indonesia.
But the pattern has shifted. Three of the great movements of people occurring in the early 21st century are from east to west in Europe, a process which began with the fall of communism; from Central and South America to North America; and from Africa, the Middle East and China to the EU and the US.
Cheaper transport, wider information, and a booming global trafficking industry, along with a need for labour in wealthy democracies with demographic stagnation, have made migration a major phenomenon of modern times. According to the IOM, the leading international body working with migrants and governments, it has a significant impact on the economies of more than 100 countries which are major senders or receivers of migrants.
Many EU countries, such as Italy, Germany and the Republic need migrant labour to work at every level of job skills. Businesses in growing economies need more workers, a factor which has for decades drawn migrants from all over the world to the US. But while globalisation allows the free movement of capital, people come up against protective barriers. The US has a quota of 200,000 temporary skilled migrants a year, but is home to an estimated five to six million undocumented immigrants, a figure that is increasing at 300,000 a year.
The vast majority of migrant workers are unskilled, and they meet resistance even from developed economies with serious deficits in labour markets. This leads to a thriving black economy, with employers often taking advantage of the vulnerability of undocumented labour to pay substandard wages. According to a 1998 EU report, the black economy of western Europe equals 16 per cent of the Gross Domestic Product, compared with 5 per cent in the 1970s.
Barriers, however, are crumbling for skilled labour. One has only to look at how avidly technology workers from countries such as India are sought by EU states and the US. Wealthy host countries benefit most from global migration, which can be devastating for the developing world. The departure of the most motivated and skilled people from African countries, for example, has left many bereft of the very people needed to sustain economic development and rebuilding after conflict.
"Some estimates suggest that in recent decades, sub-Saharan Africa has lost 30 per cent of its highly-skilled manpower primarily to Western Europe," Brunson McKinley, International Organisation for Migration director, told a conference in Addis Ababa last October. Such a braindrain contributes to the widening gap between rich and poor countries.
The flow of economic refugees is matched by the number of fugitives fleeing from conflict and repression. In Asia, there is a constant movement of refugees from conflict areas such as Sri Lanka, Burma and Indonesia, in the Middle East from Afghanistan, Iraq and the West Bank, and in Europe from the war-devastated regions of the Balkans and the Caucusus.
The worst affected continent is Africa, where several wars are in progress. Of the world's 150 million migrants, the IOM estimates that more than 50 million are Africans. Of these, five million are refugees and 20 million are displaced persons. Relatively few Africans make it to the rest of the world, as most migration is to other African countries such as Burkina Faso, Cote d'Ivoire, Gabon, Guinea Conakry, Mali, Nigeria, Senegal and South Africa.
Similarly in the Indonesian archipelago and in China, two of the world's most densely-populated countries where the populations are least stable, migration is much greater from one part of the country to another than across the international borders.
Often the only recourse of would-be migrants is the people-smuggling gangs such as the "snakeheads" in China or the Indonesian criminals who organise boats for Middle East refugees to get to northern Australia. Trafficking in human beings is global big business, with migrants often finding themselves enslaved in sweat shops or forced into prostitution or begging. The British Prime Minister, Tony Blair, has called trafficking the "world's fastest-growing criminal business".
Young women and girls are most vulnerable to abuse. Up to half a million undocumented immigrants from Africa, Latin America and Asia, enter the EU each year and three million live in southern Europe, according to the IOM.
Women workers account for 48 per cent of migrants worldwide. An estimated 175,000 young women and girls were trafficked from central and eastern European countries and former Soviet republics for the purposes of sexual exploitation in 1997, according to the Organisation for Security and Co-operation in Europe (OSCE). The main sources of the women were Russia, Ukraine, Poland and the Baltic States, it said, pointing out that Russian criminals can obtain an altered passport for less than $1,000 for under-age girls who are sold into "brutal" working conditions.
Typically, young women are lured by advertisements offering work abroad as nurses, hair stylists, au pairs, domestic workers, waitresses, models or dancers. The OSCE recently castigated national governments for failing to treat trafficking as a serious human rights issue. "Most law enforcement strategies target the people who are trafficked, not the criminal networks that traffic them," it said.
Trafficking of women in east and south-east Asia has become a major focus of international organised crime. The government of Nepal estimates there are 200,000 Nepalese women working in brothels in India, many as slaves. In Thailand, children from Burma, China, Laos and Cambodia and from hill-tribe minorities are trafficked in for the sex industry's 6,500 brothels, according to a UN body in Bangkok. Such trafficking has contributed to the spread of the HIV/AIDS pandemic.
In the past five years, the IOM has assisted half a million migrants to return home to more than 100 countries. Last month, the organisation initiated a programme to produce policy guidelines for a "best practice" approach to the reduction of such trafficking and reduce irregular migration, while increasing global understanding of what is urgently needed.
"Migration will be one of the major policy concerns of the 21st century," said McKinley. "In our shrinking world, more and more people will look to migration - temporary or permanent - as a path to employment, education, freedom and other opportunities."