  Online platforms play an increasingly important role in shaping democracy by
influencing the distribution of political information to the electorate. In
recent years, political campaigns have spent heavily on the platforms'
algorithmic tools to target voters with online advertising. While the public
interest in understanding how platforms perform the task of shaping the
political discourse has never been higher, the efforts of the major platforms
to make the necessary disclosures to understand their practices falls woefully
short. In this study, we collect and analyze a dataset containing over 800,000
ads and 2.5 million videos about the 2020 U.S. presidential election from
Facebook, Google, and TikTok. We conduct the first large scale data analysis of
public data to critically evaluate how these platforms amplified or moderated
the distribution of political advertisements. We conclude with recommendations
for how to improve the disclosures so that the public can hold the platforms
and political advertisers accountable.
