Those of us working diagonally across the US from southeast to northwest often take NE-2 from Lincoln to Nebraska City at the Missouri River, where it becomes IA-2 for the short couple of miles to I-29 on the Iowa side of the river. From there south to the MO line is but 10 miles with another 120 or so to I-70 on the east side of KC. Even though the "NE-2 cutoff" is becoming a bit congested in Lincoln, it still beats the heck out of the much longer route up I-29 to Council Bluffs, to Omaha, and southwest to Lincoln before I-80 turns due west again.
There's no chance of flooding on the NE side bluffs (unless we're talking Noah here), but the IA side runs right across the floodplain, as does many segments of I-29 south out of IA and well into MO.
With the current flooding situation on the Missouri River, I started wondering if or when IA-2 might be affected. According to the IA DOT, the eastbound lane right lane is closed already. It was similarly restricted in early July 2010 and I distinctly recall then thinking it won't take but another 2' or so of water before the entire highway will be submerged.
I can't seem to find an update more recently than June 1 (albeit after but a limited amount of search time), so it would be of great interest to find out exactly what the current situation is. Given the scale of dam releases in the Dakotas and Montana, it seems well worth watching and checking ahead before reliance on the shortcut, as every news outlet in the region is calling for rising water, and for the river levels to remain high for weeks to months.