"There has never been a migration study this big or ambitious. It was not welcomed by every nation, either. The topic of migration has some built-in tensions, and opening it up for world scrutiny risks some hazards... Around the world, the U.N. Population Division found in a 2002 survey that 175 million people were living in countries where they were not born. The number of migrants has doubled since 1975, with one in every 10 people in richer nations a migrant and one in 70 people in the developing countries. More than 11 million people moved into industrialized nations between 1995 and 2000, and more than 5 million of them landed in North America... Migrations, particularly illegal movements of people, are cause for concern in every region, most frequently for cultural or economic reasons. India fears perennial influxes of Bangladeshis, South Africa and Botswana send back Zimbabweans and Mexico does not want to be known as a transit stop for Central Americans and boat people from as far away as China. Australia has drawn opprobrium for not allowing refugees to land on its shores, or detaining them in camps if they do."
Thanks to Chris Steins