It's still roundabout but...

Going from Cedar Rapids to Iowa City on back roads is possible after all. You take US 30 to the C Street SE exit and go towards Ely. The Ely road takes you south part of the way, but then you have to take the gravel Seven Sisters Road to Polk Avenue, also gravel, and from there to 140th Street NE, a paved road, back east to Iowa Hwy 1, then south to Solon. Trucks over 8 tons are banned from the gravel sections, all of which need to be graded. This "detour" is just barely marked, by the way. There's a red flag on signposts along the way, and the occasional white pasteboard from County Supervisors about restricted access. On Iowa Hwy 1 just north of Solon, there was/might be a county mounty sitting at the Road Closed sign; the only way to go is west, unless you turn back to Iowa City.

As I suspected, Iowa Hwy 1 was washed out south of Mount Vernon at the Cedar River Bridge. Currents ripped out the roadbed, making it a total loss.