The Triumph of Polarized Partisanship in 2016: Donald Trump’s Improbable Victory

REPUBLICAN DONALD TRUMP’S DEFEAT OF Democrat Hillary Clinton in the 2016 presidential election surprised a large majority of Americans of all political persuasions.1 The same was true of most professional observers of national politics—politicians, political scientists, reporters, and commentators. In part, they were led astray by the consensus of polls, which had Clinton leading by an average margin somewhere between 2.3 and 3.6 percentage points over the last few days of the campaign.2 This was not far from her actual margin, 2.1 percentage points, as she won the popular tally by more than 2.86 million votes. But the electoral vote is what matters, and Trump’s narrow and largely unanticipated victories in the Rust Belt states of Michigan, Pennsylvania, and Wisconsin put him over the top; five of the six states that switched from Barack Obama to Trump between 2012 and 2016 were in the upper Midwest (Figure 1).3 The shock delivered by Trump’s victory arose from much more than regional polling errors, however, for virtually everything about his candidacy defied precedent and expectations. Its success challenges our basic understanding of electoral politics. It also highlights demographic and ideological fault lines in the American electorate that Trump’s presidency, by early evidence, will only deepen.