  Past research has attributed the online circulation of misinformation to two
main factors - individual characteristics (e.g., a person's information
literacy) and social media effects (e.g., algorithm-mediated information
diffusion) - and has overlooked a third one: the critical mass created by the
offline self-segregation of Americans into like-minded geographical regions
such as states (a phenomenon called "The Big Sort"). We hypothesized that this
latter factor matters for the online spreading of misinformation not least
because online interactions, despite having the potential of being global, end
up being localized: interaction probability is known to rapidly decay with
distance. Upon analysis of more than 8M Reddit comments containing news links
spanning four years, from January 2016 to December 2019, we found that Reddit
did not work as an "hype machine" for misinformation (as opposed to what
previous work reported for other platforms, circulation was not mainly caused
by platform-facilitated network effects) but worked as a supply-and-demand
system: misinformation news items scaled linearly with the number of users in
each state (with a scaling exponent beta=1, and a goodness of fit R2 = 0.95).
Furthermore, deviations from such a universal pattern were best explained by
state-level personality and cultural factors (R2 = {0.12, 0.39}), rather than
socioeconomic conditions (R2 = {0.15, 0.29}) or, as one would expect, political
characteristics (R2 ={0.06, 0.21}). Higher-than-expected circulation of any
type of news (including reputable news) was found in states characterised by
residents who tend to be less diligent in terms of their personality (low in
conscientiousness) and by loose cultures understating the importance of
adherence to norms (low in cultural tightness).
