Hajnal Line, alive and well in the modern era

Among PEW's striking findings of 2018: The Hajnal line is still in place. pic.twitter.com/MAjuTa0rGN

— Staffan (@Paradigmian) December 30, 2018

For those wondering, The Hajnal Line from Wikipedia.

The Hajnal line is a border that links Saint Petersburg, Russia and Trieste, Italy. In 1965, John Hajnal discovered it divides Europe into two areas characterized by different levels of nuptiality. To the west of the line, marriage rates and thus fertility were comparatively low and a significant minority of women married late or remained single; to the east of the line and in the Mediterranean and select pockets of Northwestern Europe, early marriage was the norm and high fertility was countered by high mortality.

The Hajnal Line has a lot of practical implications in terms of folk ways, culture and institutions, and consequently prosperity.