Iowa gave Barack Obama a resounding 9.5-point victory over John McCain in 2008. Four years later, Obama's margin shrunk to 5.8 points against Mitt Romney. But in 2016, something odd happened.
Donald Trump carried Iowa by 9.4 points — close to the same winning margin as Obama's eight years earlier — a dramatic change in the state's recent voting behavior.
Iowa had gone Republican before. It voted narrowly for George W. Bush in 2004, and it backed Ronald Reagan twice, in 1980 and 1984.
But Michael Dukakis carried it comfortably in 1988, and Al Gore's narrow victory in 2000 seemed to suggest Iowa was shifting ever so slightly toward the Democrats. That is what made 2016 so noteworthy.
Did Trump's solid victory say something about the state's fundamental partisan bent?
Yes and no. As reporter Paige Godden and the folks at Iowa Starting Line note, a stunning 31 Iowa counties voted twice for Obama but flipped to Trump in 2016. Their statewide map shows the bulk of the shifts occurring in eastern Iowa (and particularly northeast Iowa), areas of traditional Democratic strength.
While much of western Iowa has more in common with Nebraska and South Dakota (including its Republican bent), northeast Iowa has more in common with Minnesota and Wisconsin, and eastern Iowa looks toward Illinois.
The shift in eastern and northeast Iowa in 2016 probably reflects the shift seen elsewhere among working-class voters who were once reliably Democratic but responded enthusiastically to Trump's message.