Divided We Advertise: A Comparative Analysis of Post-Citizens United Political Advertising in an Increasingly Polarised United States

Political advertising is a central component of the American political system. Political polarisation, meanwhile, is rife across the US. Much research has been undertaken regarding both of these topics, but there are far fewer investigations into the convergence of the two. This paper reviews an unexamined aspect of the relationship between political advertising and polarisation in the United States. It aims to contribute to scholarship in these areas by analysing for the first time the content of political ads, using political polarisation as a conceptual framework. To determine how polarising the content of political advertising is, this study employs methods of commercial advertising analysis, adapted to create a unique set of criteria that can be used to analyse political advertising. Using these criteria, I compare the content and messaging in a sample of 72 televised political ads run in Senate races between 2010 and 2020. I lay out the results of this research by covering the different sponsors of the ads, addressing polarising issues that appeared in the ads, and showing that advertising reflected 2016 as a turning point in polarisation. From these results, I argue that Republican ads, and in particular those sponsored by Republican outside groups, contain the most polarising content and messages, and that swing states are the biggest target of polarising ads, while red states are targeted the least. I also argue that political advertising accurately reflects real-world polarisation, including the increase in polarisation brought about by Trump’s entry into politics. These results have far-reaching implications regarding the need for increased regulation of political advertising, as practised in other countries. In addition, they highlight the potential for scholars to use political advertising as a gauge of American political polarisation and the direction it is taking.