The fall of internal migration

It is costly to move, and those costs vary by culture and economic circumstances. International migration is of course hampered by immigrations laws and cultural barriers. But in most countries, internal migration is free and only restrained by costs and some degree of local attachment. In this respect, Americans are considered to be the most mobile, as they are very willing to drop everything to pursue better opportunities while the housing market is, usually, very fluid. In fact, the perception is that this mobility has even increased in the US and that it has been hampered only in the last few years, due to the current difficulties in selling homes.

Raven Molloy, Christopher Smith and Abigail Wozniak take a close look at the data and dispel some of those perceptions as myths. In fact, US internal migration has been in a steady decline for thirty years, a decline that in apparent whichever way you look at the data: by socioeconomic household characteristics and distance moved. And this has change little with the current crisis, probably because the additional incentive to move (as there is substantial evidence that some structural mismatch, including a geographic mismatch, has increased the unemployment rate recently) has been roughly compensated by the poor saleability of homes. Still, internal migration rates are still higher than almost everywhere else.

The polygyny-slave trade connection

Polygyny, a male marrying several females, is now rare except for Africa and especially Western Africa. Why would it be so prevalent in West Africa? To sustain polygyny, one needs an unbalanced sex-ratio, which is not the case there.

John Dalton and Tin Cheuk Leung claim that this is just a matter of very persistent institutions. Indeed, the sex-ratio used to be unbalanced for extensive periods in West Africa, and in a more pronounced and persistent way than anywhere else, due to the slave trade. Indeed, it took away many males from the region through the actual forced emigration, but also because of the many tribal wars associated with slave capture raids (which Dalton and Leung do not take into account).

The military draft, mortality and education

The data sometimes work in mysterious ways and provide puzzling correlations that lead to interesting research questions. One such correlation is that exemption from military service leads to lower mortality later in life.

Piero Cipollone and Alfonso Rosolia find this while looking at a natural experiment following the 1981 earthquake in Southern Italy. Boys from the affected region were exempted from military service, and they were followed, along with non-exempted neighbors, to track their life and education. By concentrating on boys both sides close to the border of the exempt region, they find that those exempt ended up being more educated. I can easily believe that, as they were not spending some of their prime learning years hiding in bushes and peeling potatoes, and they were expecting a longer work life. But the exempt also have lower mortality. This is not due to a lower incidence of military accidents, it is rather linked to the higher school completion rates. In fact, the authors conclude that raising high school completion by 10 percentage points would lower mortality by one or two percentage points in the decade thereafter. That is impressive at that age.