Media Slant is Contagious

This paper analyzes the influence of partisan content from national cable TV news on local reporting in U.S. newspapers. We provide a new machine-learning-based measure of cable news slant, trained on a corpus of 40K transcribed TV episodes from Fox News Channel (FNC), CNN, and MSNBC (2005-2008). Applying the method to a corpus of 24M local newspaper articles, we find that in response to an exogenous increase in local viewership of FNC relative to CNN/MSNBC, local newspaper articles become more similar to FNC transcripts (and vice versa). Consistent with newspapers responding to changes in reader preferences, we see a shift in the framing of local news coverage rather than just direct borrowing of cable news content. Further, cable news slant polarizes local news content: right-leaning newspapers tend to adopt right-wing FNC language, while left-leaning newspapers tend to become more left-wing. Media slant is contagious.