I’ve focused so far on shifts in the national popular vote and the number of battleground states with shifts in the vote and shifts in the result. In a normal year, these two indicators work in tandem and show us either a large or small movement toward the challenger party. As a result, I haven’t weighted the battleground-state movements by the size of the battleground states (the national popular vote usually picks that up).
But what made 2016 unique was that the incumbent party’s losses were minimal both in the national popular vote and the number and margin of movements in the battlegrounds . . . yet the election was decided by the size of the battleground states that Trump flipped. Trump won seven of the nation’s ten largest states, compared with two for McCain and three for Romney. He flipped only six battleground states, but he managed to flip four of the seven largest states. On average, Trump earned 16 electoral votes per state flipped (counting Maine as a quarter of a flip). That’s not quite as unusual as you might think, but it’s almost the highest average since 1868.
The average challenger in a post-incumbent election earns 11.1 electoral votes per state flipped, and net — including states lost and states that don’t change — adds 4.1 electoral votes per battleground in play. Only Tom Dewey in 1948 pulled in a higher average (16.2 electoral votes per flip), including 47 electoral votes in New York, 35 in Pennsylvania, 19 in Michigan, and 16 in New Jersey. But Dewey lost the election because he also gave back five states he’d won over FDR in 1944, including Ohio (25 electoral votes), Wisconsin (12), and Iowa (10). Trump’s 4.3 electoral votes per battleground in play is roughly even with the historical average but lower than losing candidates such as Dukakis and Wendell Willkie. Trump’s haul of 100 new electoral votes is less than those earned by Obama and George W. Bush and a small fraction of those won by Eisenhower, Nixon, JFK, and Carter.