To learn more about where people get their political news, Andy Guess, a postdoctoral researcher in social media and politics at New York University, recruited a nationally representative YouGov online survey panel. The nearly 1,400 panelists agreed to take part in a survey and to anonymously share data on their website visits over a three-week period in early 2015. This approach avoids the pitfalls of many previous studies, which typically ask people to recall their past news consumption — an approach that is plagued with measurement error. These website visits were then matched to estimates of media outlet “alignment” that are based on the self-described ideology of people who share articles from the website on Facebook.

The resulting data, which are reported in a new working paper by Mr. Guess, show the news diet of most respondents was remarkably centrist on average for both Democrats and Republicans alike. The two most common destinations for political news in his data were MSN.com and AOL.com, two large and relatively neutral online news portals.

But when he instead examined the total distribution of visits to political websites by party, he found more polarization. Democrats are more likely to visit left-leaning outlets like Daily Kos and The Huffington Post than Republicans are. Most strikingly, though, a sizable fraction of total political news consumption by Republicans was devoted to heavily conservative-aligned outlets like Fox News and Breitbart, which are very rarely visited by Democrats, creating a discontinuous break in the graph.