Many residents of Britain, Italy, and Belgium believe that their countries are divided socially along north-south lines. Now a study on communication patterns by MIT researchers shows empirically that such divides do exist in those countries and others.

Telecom data in Britain, for instance, reveal that only 9.5 percent of communications cross a line about 100 miles north of London. In Italy, only 7.8 percent of communications cross a line roughly along the northern border of the Emilia-Romagna region, above which lie the industrial and commercial metropolises of Milan and Turin. And in Belgium, only 3.5 percent of communications run between the Flemish-speaking Flanders region, in the north, and French-speaking Wallonia, in the south.

These invisible borders, the researchers say, help us understand social, civic, and commercial interactions in contemporary nations, and they may help government officials and other policy experts as they redraw administrative boundaries or implement programs.

“We are looking at networks to think about how communities are structured over space,” says Carlo Ratti, an associate professor in MIT’s Department of Urban Studies and Planning and director of MIT’s Senseable City Lab, who coauthored a PLoS ONE paper summarizing the results.

The findings show that for all the digital connectivity in civic life today, people still connect in “a geographically cohesive, connected set of communities,” says Stanislav Sobolevsky, a researcher at the Senseable City Lab and another coauthor of the paper, along with his colleague Michael Szell and researchers from Orange Labs, part of the French telecommunications firm Orange.

The new work builds on a previous analysis of Great Britain alone, adding Belgium, France, Italy, Ivory Coast, Portugal, and Saudi Arabia. The researchers used aggregated, anonymized data provided by Orange, British Telecom, Telecom Italia, and the Saudi Telecom Company.

In France, the researchers found that patterns of communication closely mirrored the nation’s historical administrative regions, although the data also revealed a larger east-west divide running almost the length of the country.

Ratti notes that the work might have uses in market research, but he is focused on further studies like the current one. “We’re more interested in the theory behind it and in how this can contribute to a ‘science of cities,’” he says.