2018/09/19: our social lives are shaped by a much stronger force that ignores many of these lines: distance.
In the millions of ties on Facebook that connect relatives, co-workers, classmates and friends, Americans are far more likely to know people nearby than in distant communities that share their politics or mirror their demographics.
The power of distance underlying these other patterns can be seen another way: If we were to divide the United States into two regions, merging counties that are most closely connected to one another, we would get a very simple map. It would not show the coasts versus the heartland, or red America versus blue America.
It would show, simply, all of the continental U.S. and Alaska in one region, and far-off Hawaii in the other. Divide the country further, and cohesive regions become clear at different scales. Northern Florida merges with southern Georgia. Texas and California splinter. Divide the country into 50 regions, and you get something that looks like how we might redraw our state borders to reflect the social worlds people in America inhabit today.
These networks are important in part because of other patterns that are correlated with them. Counties with more dispersed networks — where a smaller share of Facebook friends are located nearby, or among the nearest 50 million people — are on average richer, more educated and have longer life expectancies. Places that are more closely connected to one another also have more migration, trade and patent citations between them.
Counties that are more geographically isolated in the index are more likely to have lower labor force participation and economic mobility, and they have higher rates of teenage births. Some of the most economically distressed parts of the country appear to be the most disconnected.
Close-knit communities can have their own benefits, like enabling neighbors to rely on one another for economic and social support. But previous research suggests that “weak ties” to people we know less well can be particularly valuable for bringing us information we don’t already have. So people in communities that are more broadly connected may be more likely to hear about a wider range of business or educational opportunities.