  In this work we study a peculiar example of social organization on Facebook:
the Occupy Movement -- i.e., an international protest movement against social
and economic inequality organized online at a city level. We consider 179 US
Facebook public pages during the time period between September 2011 and
February 2013. The dataset includes 618K active users and 753K posts that
received about 5.2M likes and 1.1M comments. By labeling user according to
their interaction patterns on pages -- e.g., a user is considered to be
polarized if she has at least the 95% of her likes on a specific page -- we
find that activities are not locally coordinated by geographically close pages,
but are driven by pages linked to major US cities that act as hubs within the
various groups. Such a pattern is verified even by extracting the backbone
structure -- i.e., filtering statistically relevant weight heterogeneities --
for both the pages-reshares and the pages-common users networks.
