If the Source has a unifying theme, it is that migration is a defining force nearly everywhere. There are about 200 million migrants in the world, probably a record, demographers say, in both relative and absolute terms, and more than 80 per cent live outside the United States.

The Source has focused on Tajik construction workers in Russia, farmhands from Burkina Faso who pick Ghanaian crops and the Peruvians who take jobs left behind by Ecuadorean workers who have migrated to Spain.

Other themes of the coverage include the speed with which migration has grown (Spain’s immigrant population has risen nearly sixfold in 10 years) and the conflict it brings, within both nations and living rooms. Political parties rise and fall. Economic interests win and lose. Family relations change.

“None of this is easy,” Ms. Kalia said.

Nor is the process of tracking it, with migration studies a nascent field and data on many countries scarce. But the magazine has won praise from a roster of A-list scholars who read it, write for it and assign it to their students.

“It’s the best online source of information on migration that I have seen worldwide,” said Rubén G. Rumbaut, a sociologist at the University of California at Irvine and a leading authority on the children of immigrants to the United States.

The magazine is published by a Washington research group, the Migration Policy Institute, that was started six years ago to help fill the knowledge gap.

With a staff of 20, the institute reflects the mobility it studies.

... contd.