Why has the United States become so politically polarized?

Many have argued that social media, where users can find their viewpoints reinforced with slanted news stories and the partisan commentary of friends, has played a role in reinforcing tribal political identities.

That explanation has been percolating long enough and loud enough that it has even reached the Oval Office. In an interview he gave before leaving office, President Barack Obama gestured to the rise of social media as a key factor in the continuing political polarization of the United States, arguing that Americans were trapping themselves within filter bubbles, limiting their own perspectives.

“The capacity to disseminate misinformation, wild conspiracy theories, to paint the opposition in wildly negative light without any rebuttal — that has accelerated in ways that much more sharply polarize the electorate,” he said to The New Yorker.

But a new working paper suggests that the demographic groups that have experienced the most political polarization in recent years are the ones least likely to be consuming media online.