The past decade has included a notable shift in Iowa Department of Transportation policy: It never, ever, EVER wants to be stuck with a bypassed road again. EVER. After it took an act of the Legislature in 2003 to unload spurs and bypassed segments (for example, IA 923), the state has been strongly hinting to counties years in advance that improvements will come in tandem with transfers of jurisdiction.
In the most recent example, Louisa County has been offered nearly $300,000 for pieces of US 61 near Grandview that will be bypassed with a four-lane that isn’t scheduled to be paved until 2017. (You can see the plans at the DOT PIM site.) I don’t know if the offer factors in three to four years of inflation or not.