FiveThirtyEight looks at Howard County, the county in the nation with the largest presidential election swing, going from an Obama landslide to a Trump landslide. Howard County is on the edge/just outside of the Driftless Area, a region of the country that swung hard overall in 2016.
The New Yorker, meanwhile, went to the other side of the state and looked at Orange City. That area of northwest Iowa is the only one that has managed to stave off the continued population decline of rural areas, as noted in my looks at school enrollment and the peak population decade for each county.