[…] the intriguing case of Portugal.

The © panel below shows the current regional administrative boundaries in the country, overlaid atop the communications networks detected in the study.

The (d) panel shows the same picture, but layered with historic regional borders dating back to the 1930s that were later abandoned. Those old borders seem to more closely trace today's communities as people define them through their calling patterns.

The (e) panel at right shows a proposed map for redrawing the country’s administrative regions, from 1998. That proposal was defeated in a referendum.
And this picture suggests at least one reason why