From working-class neighbourhoods of French towns and cities to the villages of Algeria and Morocco, a strange kind of reverse migration is under way - of the dead.
Every year thousands of bodies are being repatriated from France to the Maghreb, as Muslim families return their loved ones to the soil of their original home. It is a costly and complicated business, involving flights, consular administrators and specialist funeral providers. It also prompts the question: why not get buried in France?
After all, France is the country where these families are now destined to live. Would it not be a sign of successful integration if France were also where they chose to rest when they died?
The answer to that question has to do with the complexities of national identity in a world of mass migration.
But also with France's own obsession with secular "republican" values, and its reluctance to give ground - literally - on matters of faith.
At the el-Ouadjib (Duty, in Arabic) funeral parlour in Lille in northern France, Abdallah Hadid receives three or four calls a day from families that have just had a death.
Abdallah Hadid in front of his funeral parlour in Lille Abdallah Hadid in front of his funeral parlour in Lille I interview him as we careen across the city in one of his hearses, racing against time to get official papers filed at the Algerian and Moroccan consulates.
"I would say about 70% of families want bodies repatriated to Algeria or Morocco or wherever," he says.
On most flights from France to the big cities of north Africa there are bodies in the hold”
Abdallah Hadid, undertaker "While the bodies are prayed over and put in the shroud, our administrative team has to rush to get all the documents: from the city hall, from the police, from the consulates. Then we get the plane tickets for the family, and pay for the coffin to go in the hold. People don't realise it, but on most flights from France to the big cities of North Africa there are bodies in the hold - between one and four, depending on the size of the plane.
"Sometimes it is the villagers back in the old country who club together to pay for the removal. It costs about 2,500 euros (£2,150).
"But more and more families are using insurance companies, paying a little every year to make sure there is the money for a repatriation when they die."According to Abdallah Hadid, there are two main reasons for sending the bodies of loved ones back to the Maghreb.
The first is the pull of the heart - memories, loyalties, a wistful longing for the "old country".
The second is a more practical consideration: the absence of Muslim cemeteries in France.
France calls itself "laic" (secular). For 100 years there has been a strict separation of religion and state.
For years, French Muslims have been clamouring for designated areas in municipal graveyards - what they call carres confessionnels. In these, Muslim tombs would be directed towards Mecca as required by religion. But they are blocked by an institutional reluctance on the part of the French authorities.
In practice, more and more Muslim areas are being created in cemeteries, simply because Muslim graves are being put next to each other. But they are tolerated rather than authorised. There is certainly no official policy to create them. Another problem for Muslims is that space in French cemeteries is normally provisional. Families take out a lease for 30 or 50 years, after which the bodies are put in a common grave.
But this offends many Muslims, who believe bodies in the ground should not be touched. They are reluctant to burden future generations with the cost of renewing the lease of a French grave, so prefer to have their bodies repatriated.