Hyperpartisan political Facebook pages and websites are consistently feeding their millions of followers false or misleading information, according to an analysis by BuzzFeed News. The review of more than 1,000 posts from six large hyperpartisan Facebook pages selected from the right and from the left also found that the least accurate pages generated some of the highest numbers of shares, reactions, and comments on Facebook — far more than the three large mainstream political news pages analyzed for comparison.

Our analysis of three hyperpartisan right-wing Facebook pages found that 38% of all posts were either a mixture of true and false or mostly false, compared to 19% of posts from three hyperpartisan left-wing pages that were either a mixture of true and false or mostly false. The right-wing pages are among the forces — perhaps as potent as the cable news shows that have gotten far more attention — that helped fuel the rise of Donald Trump.

These pages, with names such as Eagle Rising on the right and Occupy Democrats on the left, represent a new and powerful force in American politics and society. Many have quickly grown to be as large as — and often much larger than — mainstream political news pages.