Result: Miller beat Republican farmer Travis Harri, of Davis County, by ten points (55-45%), in a swing district that Donald Trump won in November by 22 points.
From Iowa Starting Line:
Republicans ran an intensely negative campaign on TV, attacking Miller for his vote on the Fairfield School Board to keep a policy on transgender bathrooms in place. The ordeal was a huge local controversy in Fairfield for most of 2016, and Republicans whipped up the anti-transgender sentiment despite a recent transgender teen’s suicide in June.
...Miller won a massive victory in Jefferson County, where the controversy burned the hottest, racking up a margin far larger than Hanson’s there in 2009.
The results by county: