We identify general trends in the (in)civility and complexity of political discussions occurring on Reddit between January 2007 and May 2017 — a period spanning both terms of Barack Obama’s presidency and the first 100 days of Donald Trump’s presidency. We then investigate four factors that are frequently hypothesized as having contributed to the declining quality of American political discourse — (1) the rising popularity of Donald Trump, (2) increasing polarization and negative partisanship, (3) the democratization of news media and the rise of fake news, and (4) merging of fringe groups into mainstream political discussions.