  During the summer of 2018, Facebook, Google, and Twitter created policies and
implemented transparent archives that include U.S. political advertisements
which ran on their platforms. Through our analysis of over 1.3 million ads with
political content, we show how different types of political advertisers are
disseminating U.S. political messages using Facebook, Google, and Twitter's
advertising platforms. We find that in total, ads with political content
included in these archives have generated between 8.67 billion - 33.8 billion
impressions and that sponsors have spent over $300 million USD on advertising
with U.S. political content.
  We are able to improve our understanding of political advertisers on these
platforms. We have also discovered a significant amount of advertising by quasi
for-profit media companies that appeared to exist for the sole purpose of
creating deceptive online communities focused on spreading political messaging
and not for directly generating profits. Advertising by such groups is a
relatively recent phenomenon, and appears to be thriving on online platforms
due to the lower regulatory requirements compared to traditional advertising
platforms.
  We have found through our attempts to collect and analyze this data that
there are many limitations and weaknesses that enable intentional or accidental
deception and bypassing of the current implementations of these transparency
archives. We provide several suggestions for how these archives could be made
more robust and useful. Overall, these efforts by Facebook, Google, and Twitter
have improved political advertising transparency of honest and, in some cases,
possibly dishonest advertisers on their platforms. We thank the people at these
companies who have built these archives and continue to improve them.
