Iowa has always surprised me that in the generals they usually go Democrat - never understood that out of a supposedly conservative, Midwestern state. Must be the big ag welfare from Washington.
Northwest and north central Iowa are the prime high-value farming areas. They always go Republican.
The more industrial eastern Iowa and some rural counties with strong Catholic presence are what tips Iowa to the Dems.
Since 1984, Iowa has gone GOP only once, 2004. They say the way to make an Iowan farmer cry is to weld his mailbox shut.