Q:

Why is Iowa a swing state?

Iowa is a weird state. There is only one other state like it in this respect, and that state is Ohio. I mean this as in these states voted for Obama and Trump by relatively wide margins. (Florida doesn't count because its swing status is due to narrow margins of victory.) Obama won both of those twice, and Trump also won both. I am curious about the swing voters. Why does Iowa seem to have such a high concentration of swing voters relative to the rest of the country?
Note: There was a place called Howard County within the state that recorded a 40 point swing towards Trump, much larger than the national effect. This was due to people changing their votes. Nationally, the shift was due to the Democratic vote total staying roughly flat compared to 2012 and the Republican vote total increasing by 3%.

A:

This isn't my particular field of interest, but this article from MerionWest is worth reading. They put Iowa's current swing-state status down to a diverse ethnic history, an ongoing rise in both urban and suburban populations, and a mix of agricultural and industrial aspects to its economy.

