https://www.reuters.com/article/us-usa-trump-russia-socialmedia/millions-of-americans-exposed-to-russian-content-on-instagram-facebook-says-idUSKBN1D15GU >About 20 million Americans may have seen Russian-backed content on Instagram in the run-up to the 2016 U.S. presidential election, Facebook Inc disclosed on Wednesday as lawmakers questioned tech companies about Russia's use of social media to try to influence the vote.